Paloma tankless--

JeffMiloJeffMilo Registered Users Posts: 13
Hi Tony,
I'm very interested in your experience with the Ph6, since you use it like I would, i.e, lighting the pilot for each use. Just need showers. Unfortuanately, only the gargantuan and expensive ph24 is still available. I wonder if you have been lighting it several times a week for several years, or can I figure on having to use a match soon. Can it be lit with a match easily?. Do you drain it after every use in the winter? Seems like would be tolerable with the right drain valves. A risk to put such a big burner in small house and anyway cold can apparently come down vent so would have to build overhang for it outside.
Anyhow I wonder what pressure you run it off of. I would need to test their assertion that 13 psi gives full performance. Any trouble with varying pressure like off a pressure tank?
Also, if the shower head is right below heater how long do you think you would have to run water before is hot enough after starting up heater and how about when you turn flow off and on during shower?
Sorry to ask so much, but any other observations/ negatives would be great.

Thanks
Milo
Off grid 10 years, 1000 watts, 12 volt, woodstove, outback inverter.
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Comments

  • BB.BB. Super Moderators, Administrators Posts: 28,877 admin
    Re: Paloma tankless--

    Not to say that Tankless never make sense... But here is a link I just ran across from another forum where people discuss the "dark side" of plumbing and tankless heaters.

    I have not read much of it yet--but what I have seen conforms with my limited plumbing experiences.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,115 ✭✭✭✭
    Re: Paloma tankless--

    Jeff,

    I'll answer on the condition that you never bid against me on Ebay,,, I am always on the lookout for another one!.. (Including a Nat. gas version for sale now!) LOL!

    I have nothing but good things to say about the PH6 and it is too bad they don't make it any more.

    To answer your questions in some order. We have been lighting it a couple of times A DAY for several years. We will light it for morning dishes, then turn it off until supper dishes, unless we have a need for more than a kettles worth of water. We will then leave it on until evening showers, then off over night. In the real world, the pilot doesn't burn much,, but every little bit helps. The ignition is a simple piezo ignitor that should last forever, and if not, one from Home depot from a Bbq would work fine. One thing that Paloma does with all the PH series is that when you first light the pilot and you are holding down the override button, it blows a great big flame so that the themocouple heats up very quickly. There is no reason that you couldn't light it with a match however.

    We do not drain it every time, only when we leave when the temp is going to go to freezing. There is some risk with the flue being open to the cold air. Especially with the pilot off, cold air COULD migrate down the flue and present a freeze danger even in a heated building. I have been thinking about designing and building an automatic stack damper that would open when the burner fired, but would close to prevent house air from migrating out the flue, and cold air coming down the flue. ON the other hand, draining is a snap. I plumbed my house with low point drains every where. These drains are underground sprinkler drains that open when the water pressure drops to ~3psi,, and close when the pressure rises to ~5 psi. So to drain, I can shut off valves on both sides of the heater (hot and supply/cold side) but I shut off the supply side, open a tap somewhere to drop the pressure, the drains open and the water heater drains. There is a hand tightened drain valve that drains the last of the valve body,, with about 1/2 cup of water.

    As for the big burner in a small house. The burner uses ~ 30k bth/hour at full bore. In the few minutes it runs I don't worry about O2 starvation. Most houses leak enough air. If yours is especially air tight you might want to do some air intake stuff anyway. I am not quite what you mean about putting an "overhang" "B" vent should vent to free air above any obstructions. Mine extends several feet above the roof to prevent it getting buried in a big snow.

    As for pressure, With a semi-low flow shower head, you really can't tell the difference between 50 psi and 30. I have done experiments, and the flow rate is good until the tank goes to 0. (Fyi if you don't know, most pressure tanks will go from bladder pressure to 0 rapidly,,) As long as the pressure is above ~10psi it works fine.

    Our water heater is ~6' of 1/2 pipe away from the shower head. It takes maybe 15 seconds for the water to be fully hot at the shower head. If you shut off the shower, and the water heater stops, and then you restart, you CAN get a little cold shot, but not usually.

    The one admonishment I would give, is that you really should have dual handled shower faucets. The problem with single handled valves is this. When you turn the shower control from hot towards less hot, you are increasing the amount of cold water, but more importantly, you are DECREASING the flow rate through the burner. The Burner flame burns just as hard, because it doesn't know the difference. The result is that the water flowing through the heater and into your shower CAN be hotter than before. This can be a real problem, because if you turn it down too far, the flame will go out, and then very shortly your shower becomes very cold! (Our winter water temperature is usually ~35F. The Ph6 gives a good shower, (small flow rate however) even with that much temperature rise.

    Other than that it works great. I have another one on a gravity feed building, with ~12 psi and it works just fine as well. I also have a old Bosch/leBlanc aquastar that has been a lot of trouble over the years, mostly due to debris in the gravity water. I also have a PH12 in service at another remote site, as well as a PH24. I am not a fan of Boschs, but my neighbour swears by them.

    Most of the parts are still and will continue to be available, and repairing them is quite easy,,,if you ever need to. Shout if you have other questons.

    Tony
  • JeffMiloJeffMilo Registered Users Posts: 13
    Re: Paloma tankless--

    Hi Tony,
    Thanks for the thorough reply. After posting here I got kind of flattened by finally connecting with supposedly the top technical word at both Rheem/Rinnai in the midwest I think and Paloma in California. Really pushed to get to top of tech food chain on this. I wanted confirmation that the ph24 or 12 would give "full performance at 12.9 psi" (the ph12 at 10 psi.) as the manual and other literature says. I explained my situation as needing to run heater off first a pressure tank with a 40--20 switch and then when tank emptied directly off a booster pump from a cistern giving 15 psi at 2.5 gpm flow rate. (12 volt flowlight booster). Heater only connected to a showerhead 4 feet from heater and lower to boot, not any other spigots. I was told emphatically that even in this ideal situation heater would perform very subpar if at all at any pressure below 40. Not even the 2 gpm/70 degree rise I'll settle for. Was told the 12.9 psi refered not to pressure input at heater as I assumed but to the pressure differential between input and output of heater allowed. One can improve things by removing flow restrictor but no one knows how much. You would think that with all the decades these have been sold they would have hooked one up to a spigot and tested at different pressures, then published the info. A third top guy at Low tankless (almost the only retailer) agreed the literature was very deceptive and claimed they had complained to paloma repeatedly but paloma is not listening.

    Anyway you have had a very different experience with a Ph12 running at full specs, I guess, at 12 psi so I don't know what to think. What would be their interest in lying to me and losing a 1300 dollar sale?. But then, How could you possibly be wrong?. Normally I'd tend to trust your test and get one but only the ph24 is available in propane and too much money to lose, so guess I'm done with it. Too bad.

    My reference to an over hang meant I was thinking of mounting one on outside wall since Ph24 burns something like 150k, and thot a simple overhang would be enough.
    I'm curious why you run so many of these and/or the takagi. Did you say 6?

    Jeff
  • BB.BB. Super Moderators, Administrators Posts: 28,877 admin
    Re: Paloma tankless--

    What about RV Water Heaters... Like this one. 35,000 BTU tankless

    35,000 BTU per hour * 1/70Frise * 1/60minperhr * 1/8lbpergallon = 1 gpm

    Or a 6 gallon 12,000 BTU tanked unit. Warm up the water, then turn it off for 12 gallon shower... etc.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,115 ✭✭✭✭
    Re: Paloma tankless--

    Jeff,

    To answer your questions is some sort of order again,

    First, We do/have caretaken a remote bush camp with numerous cabins, each with their own water heaters,, plus a couple of community building with them. As for the Takagi's I have installed them in a number of grid tied houses and have had great success with them as well.

    Second, I would never mount one outside if you are in a freezing environment. If you are worries about combustion air, then figure out how to provide it in an enclosed space. Keeping a Ph series from freezing outside would be difficult at best.

    As to you question about pressures. It would be helpful to my thinking process knowing what your needs (gpm/temp rise/time interval) is so that I can think it through.



    I can only relate anecdotally with my experience. 1 of my PH6's is on a conventional p-tank system and gives a good flow rate (small,, as the heater is small, 70f rise,,~3/4gpm) from the p-tank. 30-50 psi if memory serves. It will still continue to produce as the pressure drops until just before the tank runs out.

    I have another Ph6 connected to a seasonal cabin with a gravity feed system, that puts out ~ 12 psi. (I have never measured the pressure, but the tank is ~ 30' high, so using the psi/head formula of .43 psi per foot of head (minus friction losses) leave me ~12 psi) This unit is only connected to a kitchen sink, and all I know is that I have plenty of hot water at the sink. This unit only operates with ~ 40 rise as it is summer only

    A third unit, and I confess I can't remember if it is a PH12 or 24, but it runs at about 12 psi in a large commercial kitchen, It puts out all the hot water we need there as well, (probably too much!) Summer only,, 40 degree rise as well.

    We also have number of standing pilot boschs, most that run on boosted pressure, but still low volumes. These have been more problematic over the years, being more sensitive to pressure changes.

    Bill makes a great suggestion, in that a RV heater will heat water pretty quickly, (in small quantities) but not very efficiently. But if all you are looking for is a simple shower or hand sink, it might be the way to go.

    Give us a better idea of what it is you are trying to accomplish,

    Tony

    PS, I'm not sure the Rheem/Lowes Paloma USA people have a clue. Your best bet would be find some one to do a real world test with a PH 12/24 and see what happens. As I said, knowing what YOU are trying to do would help.

    T
  • JeffMiloJeffMilo Registered Users Posts: 13
    Re: Paloma tankless--

    Hi Tony and Bill,
    What I am trying to accomplish is to get a 2gpm shower with a 70 degree rise. My house is fed by a Flowlight d.c pump sitting in a cistern. The pump is the best d.c booster pump available and supplies a pressure tank that is switched to do 40--20 psi pressure . I don't use a 50-30 switch because I was told 40-20 would save the pump plus 50 psi is uncomfortable and wastes water. When the pressure tank empties while using water the pump runs the fixture directly. Currently I have a wood fired shower setup (from a cannabilized old gas water heater) in an outdoor shower house but intend to move back inside. Staber clothes washer does fine cold water and dish water heated on wood stove. A pressure gauge has been installed in a tee and when shower is running at 2.5 gpm and pressure tank is empty the gauge reads 15 psi. So i would have to run a tankless on a range of 40 to 15 psi, unless I'm very careful to only use shower when 25 gallon pressure tank is fullish. But they say even 30 psi is too little. Really nuts. Maybe your gravity feed heater works okay cause you only have 1/2 gpm flow?. I'm aware of course of coils in wood stove etc. but such systems have there problems especially with single story house and was looking for propane alternative. But supply is difficult so wanted to save on propane. propane tank heater 30 gallon second choice but they probably don't intend you to be lighting it for each use so piezo's need constant replacement and they don't make modern sealed ones easy to light with a long match plus after a few years the tank will bust even with anode changes and there goes your floor. plus the big objection that you are wasting gas by allways heating 15 gallons to lukewarm just to get another hot 15 gallons on top
    Thanks for your ideas Bill. They are good ones. The 35k RV tankless heater tho will only give maybe 1 gpm to get 40 degree water in cistern up to 110. The tank type would be great cause 12 gallon size better then 30 but i worry about longevity. I imagine but don't know that they use pretty light steel to keep weight down plus they just don't make RV stuff to last, you would think. But, it's a possibility. Have you ever seen one?
    Tony-- I thought a paloma could be put outside because it would be acceptably easy to flip 4 gate valves before and after each use to drain to prevent freezing in the winter. Easier then starting a fire each time. Are you saying you would not trust the draining?

    My situation is partially similiar to normal people in that most people on wells use a pressure tank and use a 40-20 switch out of preference,(while for me 40/20 is partially necessary) ,so it doesn't matter that they have a grid connected 50 psi well pump. Tankless companies are missing out, it would seem.

    I don't know why this topic was not not put on main new posts. Have to do something about that.

    Cheers,
    Jeff
  • BB.BB. Super Moderators, Administrators Posts: 28,877 admin
    Re: Paloma tankless--

    I don't have enough experience to say the RV heaters will last or not--but I would tend to agree with you that they probably are not 12 year tanks with 365 day use.

    Also, from what I have seen, hot water heaters are very sensitive to water chemistry.

    I was looking at the price ~$120-$350--$550 or so--depending on what you got. 1/10 to 1/3 the cost of a "high end" tankless water heater. Even if they only last a few years, the replacement costs over 10-20 years is almost a wash--especially if you try and don't like the "cheap" ones--they are so much cheaper than the more expensive units.

    Regarding efficiency... At least on heating water--a tankless is around 80% efficient, and a small RV heater may be around 70% efficient--if you turn it off between uses. Not a huge difference in fuel usage.

    If you want 70F rise on 2gmp, assuming 80% efficiency and 8 lbs per gallon of water (I like simple math to estimate what is possible or not):

    70F rise * 2gpm * 60min/hr * 8lbpergal * 1/0.80 eff = 84,000 minimum BTU burner for tankless heater...

    Other ideas--can you put a 30-50 gallon drum in the heated space of the cabin to preheat the water to 70F room temperature (or more if next/connected) to stove?

    In the end, people like Tony/Icarus have much more experience with water heaters in the bush--Better to listen to him than to me. :p

    -Bill

    PS: Are you having problems with finding new posts to this thread? "New Posts" seems to always work for me, and the thread is at the top of the "Solar Water Pumping" forum. The only thing you might not see is if somebody goes back and edits their post with new information--that will not appear as a "new post".
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,115 ✭✭✭✭
    Re: Paloma tankless--

    My first thought is do you really need 2gpm shower? I know that the PH6 will deliver a pretty darn good shower, with incoming water ~35f. (Remember that @70f degree rise, from 40f, means water ~110f. Most people would need to add some cold tothe mix to avoid getting scalded, so the water heater may only need to heat 80% of the total flow). Our pressure tank delivers enough water for 2 good showers before the pump kicks in. What you can do is tweek the on off pressure, so that the pump turns on early, relative to the volume left in the tank, so that the pump AND the tank deliver part of the water later, rather than waiting for the tank to drop,, and then relying on just the pump. My shurflo pump delivers ~2 gpm @30psi, if I am drawing 3gpm, I get in essence 1 from the tank, 1 from the pump, increasing the run time at full flow.

    I know that the PH6 WILL work quite well in this situation,,, my hunch is that a PH12 will work also,,, possibly as well.

    As for an outdoor install,,, it just seems like it is inviting headache and heartache. Draining a system everytime you need to use it is a bit of work,,even if you have planned carefully. I would put the heater right near the shower. Ours is just outside the shower so that we can adjust the flow rate without leaving the shower if we need to.

    Tony

    PS If you move the P tank, and or have an additional tank in the heated space, the water will have a chance over the day(s) to temper a bit, decreasing the temperature rise required. A solar batch tank,,would be the bee's knee's.

    T
  • JeffMiloJeffMilo Registered Users Posts: 13
    Re: Paloma tankless--

    I wonder why my Flowlight is only giving 15 psi, 2.5 gpm and you are getting 30 psi on a shurflo which is not rated as powerful. Guess I need to start at the pump, measure pressure there etc.

    Yep, would be great to find someone to test there heater with high heat output and flow ---low pressure as you suggest. I don't imagine you feel like doing that with your gravity fed Ph12?. I know, lot of work.

    At first glance it looks to a newbie like the "new posts" section lists all the new posts as some sites do. Just realized that the new post disappears after you read it. You can't cover reply changes in several posts in different sub sections from one page. Thot there was an error.

    Jeff
  • BB.BB. Super Moderators, Administrators Posts: 28,877 admin
    Re: Paloma tankless--

    There are a couple things you can do to track a thread... One, after you have read all of the "new posts" (covers posts from every sub-forum). Click on:
    You may search for threads updated during the previous 24 hours, here.
    I use this a lot to look for a thread that I had just read in the last day--if I want to add more information.

    You can also use the Forum Tools (near middle at "top" of page in blue bar) and "Subscribe to this Thread"--and you can step your email to notify you when a thread you are watching gets a new post.

    Go to "User CP", "Edit Options" (this should link directly) and look for:
    Default Thread Subscription Mode

    When you post a new thread, or reply to a topic, you can choose to automatically add that thread to your list of subscribed threads, with the option to receive email notification of new replies to that thread.

    Default Thread Subscription Mode:
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    May be of use to you (or--you may end up not using it because you get too many emails already). ;)

    Hope this helps.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,115 ✭✭✭✭
    Re: Paloma tankless--

    Jeff, I can't do anything with the Ph 12 until sometime in August if then. I don't work for the people that own it any more,, and they only have their water system up an running for a few weeks in August. Often times, I am away at the time the are there,,, for reasons I don't need to elaborate one. I will try in August if you send a request and if I can.

    As for your pump. The shurflo 9300 submersible puts out 1gpm at 100psi, I don't have the chart handy, but at ~50 I think it puts out ~3 gpm.

    http://www.shurflo.com/pages/new_industrial/industrial/agriculture/subcategories/9300.html

    I still ask the question as to whether or not you need a 2.5 gpm shower.

    As an addendum to my previous post, In addition to a batch preheat solar tank, you could also add some coils to your stove to a circ. tank to preheat water as well.

    Tony
  • JeffMiloJeffMilo Registered Users Posts: 13
    Re: Paloma tankless--

    Hi Tony and Bill

    You got me thinking about my pump, Tony. I should have questioned that 15 psi. Put in this system many years ago and forgot totally that the flowlight #2920 is rated to put out up to 65 psi and 4.5 gpm! So something is screwy. I know I used amply oversized pipe to house but once there it does go thru 30 feet of unnecessary 1/2 or 3/4 pipe allready in house before the gauge that I could bypass but my distant memory of pressure loss charts tells me that's too short to cause big pressure drop. I'm going to have to step back and figure this out. Most of my self education was in electricity, and I've forgotten a lot of that!. It is a booster pump not a submersible like your shurflo. I use an old sunrise submersible
    at 300 feet to lift water to 2000 gallon cistern at about 1-1.5 gpm, then the booster takes it to house and pressure tank.

    I could probably settle for 2 gpm, maybe even 1.5, but the 3/4--1 gpm?, I don't know. Call me spoiled. Bottom line is the ph6 is not for sale, nor the 12. If I saw a good deal on Ebay on either I might try it. Would prefer a 12. Course you'd have to tell me you weren't bidding. hah! There is that RV tankless (Excell) that is same size as Ph6.

    With all the decades the legacy has been out there it's amazing there's not more tested info out there, and that none of the dealers or manufacturer cares.

    Thanks for the posting tips, Bill
  • icarusicarus Solar Expert Posts: 5,115 ✭✭✭✭
    Re: Paloma tankless--

    30' of 1/2 or 3/4" pipe is not going to serve enough of a restriction to drop the pressure much.

    Try this shower head,, with 30 psi it puts out a GREAT shower!SHOWER HEAD saves water, good spray on less than 10 pounds pressure



    For low pressure gravity feed water. Gives a good shower on 7 lbs. pressure, best with 10 pounds. Solid brass, chrome plated. http://www.backwoodssolar.com/

    Tony
  • BB.BB. Super Moderators, Administrators Posts: 28,877 admin
    Re: Paloma tankless--

    I don't know what size pipe you used--but there can be a problem with oversized pipes (large diameter with low flow rates) on systems that have sediment laden water--the sediment can settle in the pipes and restrict water flow.

    But if you have a 2,000 gallon tank--you probably don't have that problem--Other obstructions in piping/valves, failing pump, waterlogged pressure tank?

    :confused:

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • JeffMiloJeffMilo Registered Users Posts: 13
    Re: Paloma tankless--

    Thanks for the ebay tip Tony. I'd really like to find someone reputable that could test a Ph12 for me, even for a fee. Hard to plunk down 600 bucks for a unit from god knows who with no warranty. Got to find the time to trouble shoot my system, see why I'm only getting 15 psi.

    Jeff
  • icarusicarus Solar Expert Posts: 5,115 ✭✭✭✭
    Re: Paloma tankless--

    After reading through all the posts,, and reading the spec sheets on the Flowlight I think you have a problem with your plumbing/tank/pump system.

    All things being equal, I there is no question in my mind that a PH 12 would do just fine in your system, assuming you could get somewhere near the spec. 4 gpm+ that that pump should deliver at 30-60 psi. According to the PH12m specs it should put out better than 2gpm at 70f rise. (Most showers are ~105-08f,, less 70 is 35-38f water,,,, doesn't get much colder!)http://www.tanklesswaterheaters.com/palomaspecs.html

    You certainly should be able to maintain a 2-3gpm flow rate through the system with that pump,,, assuming that you don't have some obstruction that you don't know about. I assume that you have looked at all the valves to make sure they are fully open. Do you have excessively hard or silty water, perhaps leading to build up in the pipes? It might be an interesting experiment to run the pump full bore without being connected to the water system and measure the no pressure out put. Then, if you can't isolate you p-tank easily, plumb in a small pressure tank, (boiler expansion tank for example), let the pump pump it up to say 50 psi, and measure the flow/recharge rate then.

    I had a PH 12 in a house for years, and it ran on 30-50 psi, always giving a good shower.

    Tony
  • EcnerwalEcnerwal Solar Expert Posts: 101 ✭✭
    Re: Paloma tankless--
    JeffMilo wrote: »
    Got to find the time to trouble shoot my system, see why I'm only getting 15 psi.

    Jeff

    Fixed a "mysterious low pressure at one faucet" when replacing a tub last year - some idiot had dumped enough solder into a vertical joint that they had almost blocked an elbow - there was a tiny passage for water to get through, which was why that faucet always had low flow. Fairly difficult to track down, as I was not the idiot in question, and it was not particularly near the faucet. Just kept ripping back until I got full flow, and then re-plumbed it right.

    If you have something similar (a drastic restriction somewhere) you should be able to measure (when you figure a way to attach a pressure gauge, if you don't have several scattered about) full pressure with no flow, but the pressure would drop off drastically as you got any flow. In that case you'd also expect pressure to remain high at the pump. If pressure is falling off at the pump (being the most likely place you already have a pressure gauge), you may have a restriction on the intake, or some problem with the pump itself.
  • icarusicarus Solar Expert Posts: 5,115 ✭✭✭✭
    Re: Paloma tankless--

    As a full test,,, there is no reason,,, except for the hassle factor, that you couldn't run a length of 3/4 poly pipe to you shower/water heater directly from your P-tank and see how it flows,, both pressure and volume. That would isolate and determine if you have some sort of flow restriction that you may not know about.

    T
  • JeffMiloJeffMilo Registered Users Posts: 13
    Re: Paloma tankless--

    I had a PH 12 in a house for years, and it ran on 30-50 psi, always giving a good shower.

    Tony[/quote]

    That's informative, but will it work on the 40--20 switch I really prefer to run?. The 15 psi is only when p tank empties and I am running solely off pump. Any problem that may exist with pump may be fixable, but would still be left with that low of 20. Was told originally that running pressure up to 50 regularly would wear out pump a lot quicker, plus 50 just seems like it would feel excessive. Not good enough objections I know. Real issue is when pump takes over. I've got to figure that, and will starting Saturday. Everything around here suddenly needing too much attention.

    I just read an old blog from 1989 by a Neil Green at Low energy responding to a failure someone had (Homepower#9 Q&A) running a ph6 off gravity. Neil says putting a 12 volt pump in line between water source and Paloma and switching it on for each use will work.

    How much internal air space did you have to run that in, and did you shut down other heaters etc. first? Ph12 is 89k btu's and this house is a somewhat tightly built 1000 sg. feet. And Of course I can't open all internal doors for each use. Did you find it helpful to have the heater right next to shower to make adjustments?

    J
  • icarusicarus Solar Expert Posts: 5,115 ✭✭✭✭
    Re: Paloma tankless--

    Once again,,, I try to answer your questions in some order,

    I think if you run either the PH6 or 12 at 20-40 as opposed to 30-50 you wouldn't notice one iota's worth of difference in the real world. I don't have an opinion on the subject of early pump failure, but my hunch is if the pump is well built,, it really isn't going to have much effect on pump life.

    We have run several demand water heaters that are gravity fed, with small shurflo boosters with small pressure tanks and the results have been fine. (Bosch units)

    By internal airspace I assume that you are referring to combustion air. A simple calc. I have used in the past is the following Formula for combustion air:Take the cubic footage of the enclosed room. (HxWxD). Multiply by 20. If the resulting number is greater than the INPUT btu of the unit, it is OK.

    I would not take this to the bank, but it gives you some idea of how much air a burner needs. So your 1000 sq ft, with 8' ceiling would give you 8000 cu ft X 20= 160kbtu.

    In the real world,, I don't think that most houses are built tight enought to worry about a few minutes of water heater use depleting 02. A furnace that might have a duty cycle of say 50% over 24 hours, or a woodstove burning 24 hours and I think you might have a problem. Think of how many cu ft of air comes in when you let the dog it for example.

    If you were to put the water heater in a sleeping room and you were going to sleep while the whole family was going to shower I might worry.
    You could always cut a hole in the wall, with a closeable damper that you opened while the heater burns, close it when it is off. It is tough fabricate a direct vent system for the standing pilot heaters as they rely on draft hoods for good draft, so any intake air floods the room, rather than just the burner.

    Our heater is just outside the shower because that was where it was easy to install. The side benefit is that I can reach our and turn it up or down if I need to,,, usually, it just stays where we have it set. The attached picture shows the relationship between the heater and the shower. The pipes at the bottom of the heater are the drains,, they now extend down and drain under the floor.


    Hope this helps,

    Tony
  • JeffMiloJeffMilo Registered Users Posts: 13
    Re: Paloma tankless--

    Hidy ho, good neighbors.

    While mulling over Tony's excellent last post I got distracted into playing with the numbers Bill gave on 2/16 considering a 10 gallon r.v tank heater. For the sake of general educational speculation let me throw out this idea, (which I don't want to actually implement but someone might). Leaving out efficiency, it takes 5810 btu's to heat 2 gpm 70 degrees and take a 5 minute shower or to heat a 10 gallon tank 70 degrees and use it for 5 minutes. With the tankless at 80% you actually burn 7262 btu's. So my idea, for the sake of others, is this. Get a 60k btu Camp chef single burner and put it in a dedicated vented shed on the outside wall of your bathroom. Put a 10 gallon electric tank on it and light. Assuming you lose the same 20% as the tankless due to heat going out to sides etc., instead of up a vent, (how could it be more?) you'd still burn 7262 btu's which means only 71/2 minute wait. Hang a loud timer on your belt. Even in the rare event that you space out the PTR valve should save you. No problems with freezing heat exchangers, pressure, flaky R.V parts etc. Only problem is the added efficiency loss of the fact that with a tank you have cold water entering as you shower, so you don't really get 10 gallons at desired temp. Have to heat water hotter but how much is unknown. Any opinions on the amount of loss here? I intuit it would not be not too bad. Maybe they don't make electric tanks with as stout a bottom, who knows?, but they are a lot cheaper.

    Bone head simple and thus durable.

    Jeff
  • icarusicarus Solar Expert Posts: 5,115 ✭✭✭✭
    Re: Paloma tankless--

    Jeff,

    I think you are playing with fire,,,, no small pun intended.

    A few potential problems jump right out. For example,, how are you going to keep the fire contained under the water tank? If the tank is foam insulated,, I see a pretty easy case for igniting the foam. My guess,, only that, is that containing that many Btus and not having them escape out the sides is going to be a tall order. I could see melting the sheet metal cover of the tank as the fire climbs the side of the tank,, like a soup pot on steroids. I also see that this outside tank and it's supply and discharge lines are going to be subject to freezing. On the other hand,, buy a propane tank water heater and install it outside as you suggest,,, my guess is that this would be way more efficient. There is a reason that gas water heaters have the flue running up the middle of the tank.

    I think that you are making this all too complicated.

    A much simpler solution is a Zodi outback shower. Place one end in a bucket, one end in the shower. Put the heating coil on the stove, and bingo,, hot water. The volume is low, but you can get it real hot, and add in some cold with a mixing valve and a second pump.

    http://www.zodi.com/web-content/

    We used one for years. We heated water on the woodstove until it was a bit cooler than we liked for showers,,, then pumped this preheated water through the coils, and had a pretty good shower at -40. On the other hand,, the current system works great with almost no headache.

    T
  • EcnerwalEcnerwal Solar Expert Posts: 101 ✭✭
    Re: Paloma tankless--
    JeffMilo wrote: »
    So my idea, for the sake of others, is this. Get a 60k btu Camp chef single burner and put it in a dedicated vented shed on the outside wall of your bathroom. Put a 10 gallon electric tank on it and light.

    Sounds like a flaming shed, then a flaming house, and really hot shower that leaves you fithy and covered in ashes. If you want a gas water heater, buy one, don't set an electric one on fire with some homebrew thing that will void your insurance....
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Paloma tankless--

    void your insurance? heck, it could void your life. that could be right up there with my niece (blond and 19 at the time) having a cookout indoors with her charcoal grill.:roll: you guessed it, she's ok because she has dumb luck.
  • JeffMiloJeffMilo Registered Users Posts: 13
    Re: Paloma tankless--

    Your warning about heat travelling up the sides is a good one. I thought of that but forgot to mention one should remove the outer cover and insulation. With intermittent use of 3 times a week insulation not too important as you're going to lose the heat anyway. Pipes are easy to protect from freeze and easy/cheap to replace. It would be more efficient then a 30 gallon gas heater for a single person because you wouldn't have to partially heat 20 gallons to get 10 gallons of hot at the top, plus the big advantage of being so much quicker. But still, It requires a focused person with a good belt timer and I certainly would not recomend it to most. One's perspective changes tho, when propane is 50 miles away one way, as you probably know. 200 lb. tanks are the way.

    The paloma 12 is not available from any one with a phone and address. Best thing for me would be a paloma 5.3 electrically controlled propane unit kept totally off between uses, because it comes in direct vent. D.V is cool cause it eliminates freezing risk (no negative air) and combustion air issue removed. (Tho as you say that maybe not a real issue, but it's nice). Wattage is minimal, once standby is eliminated. My coffee maker uses more. I would raise my switch to 50--30 and either fix pump issue or only shower when P tank is fullish. But Paloma is really firm about needing 40 psi., minimum and they don't even like that!. Business is good I guess. They don't care.

    Will look at that Zodi. Then maybe I'll tear down the house and rebuild one that is 30 feet tall so I can put a coil in my stove. Problem there is I have duly noted your good reminder that I'm making this too complicated so Id feel guilty. And every one would laugh at me.

    Thanks, :D
    Jeff
  • icarusicarus Solar Expert Posts: 5,115 ✭✭✭✭
    Re: Paloma tankless--

    Where are you getting the information that a Paloma needs 40psi? I don't think that is right. I can't find a link right off,, but if memory serves it works up to spec at ~15 psi. As I have said,, one of my PH6s runs just fine on ~12 psi. (33' of head)

    You could also look at the bosch standing pilot series, as well as the one that is autolight with a flow activated dynamo.

    To add one more idea,,, Rinnai,, a company that I have also had good luck with sells a standing pilot heater, that will run on as low as 5 psi, with proper performance ~11 ps. I have never seen one of these, and I can't seem to find them on the Rinnai site,,, but what the hell: http://cgi.ebay.com/NEW-Rinnai-Outdoor-Tankless-Hot-Water-Heater-Stainless_W0QQitemZ270348204496QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item270348204496&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

    I think the idea of putting a fire under and out door tank is not a good idea,,,,

    Tony
  • JeffMiloJeffMilo Registered Users Posts: 13
    Re: Paloma tankless--

    You could go to these sites, but don't just look at spec sheet, download the manuals.

    http://www.tanklesswaterheaters.com/ph20rdv.html

    http://www.tanklesswaterheaters.com/palomaph12m.html



    On page 15 of the PH20 manual (electric ignition/propane heater), you can see
    * "a pressure of 40 psi is required to get maximum flow". Maximum flow is defined on spec sheet as 3.3gpm/70 degree rise. We only need 2 gpm/60 rise but they won't reveal if you can get that or at what pressure.

    * Using a well pump a minimum pressure of 40 psi is needed

    the spec sheet says minimum pressure is 14 for ph20. but you can see in the manual that you must add to this the pressure loss of everything downstream of heater to get minimum pressure, and the implication here is that with this minimum you will only get minimum flow of .66gpm. So in my case if I lose a hypothetical 5 psi in the 4 feet of pipe plus shower head on output of heater then I need 19 psi just to get .66 gpm as I read it. Same addition applies for figures for PH12, of course.

    On the PH12 the manual says on page 6 that the minimum is 2.4 and full performance is 10 psi. Sounds great! so adding the above hypothetical you need 7.4 to start flow and 15 psi gives full show,(still not great for gravity) whereas with the PH20 it takes 18 or 19 psi just to get minimum flow. However it ruins everything by saying, once again, that pumps need 40 psi. So you call them.

    I hammered thru to talk to a "Senior Tech", whatever that is. On call for each model. Just got a flat statement that they need 40 to do anything at all. Even just one fixture hanging off end of heater. Rediculous. According to low's tankless they have had many complaints about pressure and false/misleading specs from customers and attempts to return units, but of course, as usual, he knew no details.

    Takagi's, Noritz's, etc are worse, and they don't warranty owner installs. New Bosch's all say minimum 30 but want more.

    Regarding your statement on the Ph6 and gravity. What you actually said in that earlier post was that your gravity ph6 was #1--only hooked to a hand spigot,( so this means not being tested at 2gpm), and#2--that only temp rise was 40 degrees in summer. So not a good indication for the present required target figure.

    Do you know how to measure or figure the pressure loss in 3/4 inch pipe/ft. plus typical full flow shower head at 2gpm without breaking pipes in two places and installing gauges.?

    Regards,
    Jeff
  • icarusicarus Solar Expert Posts: 5,115 ✭✭✭✭
    Re: Paloma tankless--

    Jeff,


    I'm not sure I really see what the problem is here.

    That is the spec for a PH 20. That is not a "legacy series" Paloma that I thought we were talking about. My guess it that the PH 20 is like the Rinnai, the Takagi, the Nortitz, and some of the Bosch's. They are a much more high tech/high ef heater that is design for good stree pressure,,, and not as well suited for small cabin type applications I am away from home right now so I don't have a Ph6-12-24 legacy spec sheet handy, but reading from a PDF manual (http://lib.store.yahoo.net/lib/lowenergysystems/paloma.pdf) the PH-6 requires 4.3 psi for full output. The 12 has a min of 2.1, with full performance @ 10psi. The 20 has a min of 2.4 and full @ 12.9psi.

    In the real world, the output is regulated mostly by flow rate, not pressure. The importance of pressure is largely limited to ability of the burner to light due to CHANGE in pressure upon opening a faucet. With limited pressure, if you turn the heater down, the effect on the diaphragm is to reduce it's ability to sense change, and risk shutting off because the pressure is too low. Above a few psi,, it really doesn't matter to the diaphragm. The real limitations to these heaters is the tendency for the output temperature to change as the flow rate changes, hence the suggestion to use dual handled faucet controls.

    In a similar gravity system, using an older AquaStar heater, we had to run a dedicated line all the way from the tank to the heater that carried only water to the heater. What would happen is, when plumbed into a common supply with the cold, when the burner was burning, you would be in the shower, and by turning on the cold to temper the water, it would drop the pressure enough that the burner would quit,,, and in about 15 seconds you would be showing in frigid water! Try as I might to mitigate this, the only solution was to run a complete line, all the way into the gravity tank so that no other faucet could effect the water heater. Works perfectly ever since.


    As for my gravity PH 6: (I confess I have written enough about this lately I have forgotten much of it!) I have only run it on ~12 psi for on sink. The intake temp is a summer tank that can be ~70f. All we use it for is the sink, so I have never checked to see how many gpm it puts out,nor what the max rise would be in that situation.

    What I can tell you is this,,,,,,My PH 6 works GREAT with a low flow head, taking ice water out of the lake, and giving me all the shower I need (too hot in fact!) My P-tank is set for 30-50, and we both can take a shower without the pump needing to run. (The tank does call for water, but depending on my mood I may shut if off to pump again in the morning) I would guess that my P-tank is ~50 gallon rated, leaving ~25 gallons of water. At 2 gpm that leaves~ 12 minutes of shower,,, without the pump coming on,, short but enough. (I'm quick,, Susan a bit slower!)

    What I can also tell you is that the PH12 performs much like the 6, and would be similar except for a significantly larger output.

    Tony
  • JeffMiloJeffMilo Registered Users Posts: 13
    Re: Paloma tankless--

    It seems as though you didn't really read my post or look in the manuals. My post
    was simply designed to answer your question as to where I was getting a figure of 40 psi for the paloma PH20 that I had referred to in my previous post. Basically I said that the manuals for all models(even the legacy) add confusion by saying you need at least 40 on a well pump, and that when you call them they say you need 40 regardless. You also quoted a memory of 15 for that model and I explained that was only a minimum required for minimum flow, (I don't want minimum flow), and that in addition downsteam resistance must be added to all these specs.

    I don't understand why you say you don't have access to the spec sheet when you are obviously on a computer and I have given you the links for specs and manuals. In addition I gave the relevent specs in my post for both types of heater.

    If you look you'll see I did deal fully with the the Legacy, tho I did misquote the spec on ph12 as being 12.9 which is for the ph24. Have changed this to the correct 10. To repeat, if you have 5 psi downstream resistance you need only 15 psi for full performance on the ph12. However they muddle things by saying you need 40 on a well pump (why would there be a differance between pump and any other source?) and when you talk to them they basically say specs are bs and you need 40 from any source.

    So such confusion and incompetance on their part caused me to start this post and find out how low you really can go, basically based on other people's experience. While it has been good to learn that your PH6 gives max temp rise at 30 psi no one on this blog is giving anything conclusive, i.e, specific for any lower pressure, cold temps, which is what I was looking for evidence for. Even 20 psi. Since Paloma has muddied their specs you have to doubt them. And it is not true that whatever is true for the ph6 should be close to what the 12 can do. The diff between their full performance specs is 5.7 psi (4.3 vs 10).

    Possibly the idea I threw in a few posts ago of putting in a 12 v pump right before heater would work if you first turn on tap and then pump, but no one here has apparently tried that or had a specific comment. Beating a dead horse at this point I guess.


    Good luck to all
    Jeff
  • icarusicarus Solar Expert Posts: 5,115 ✭✭✭✭
    Re: Paloma tankless--

    Jeff,

    When I make the comment about not having access to the info,, I am referring to my library of paper copies of install manual, service manuals etc.

    It seems that somewhere along the line you changed from asking about the legacy series to asking about the newer style.

    I can only speak to my one experience with the legacy series. I have NO experience with the newer series, and some limited experience with Tagaki, Rinnai and Bosch tankless heaters.

    Now,,, reading (admittedly a quick read on line) the PH series specs, installation PDF, I can fine NO reference to needing 40 psi. That may in fact be true with the conventional series,, but as I say, I can't find the reference you cite.http://lib.store.yahoo.net/lib/lowenergysystems/paloma.pdf

    Now,, to condense all that I know about the legacy series. I have noted in precious posts that we have installed booster pumps with small pressure tanks on gravity Palomas and Bosch's with good results. My system with the p-tank and pump provides a great shower, pulling 33f water. IMHO a Ph12 would do at least as well, there is no reason to believe that since it is essentially identical except for it is just bigger, that it wouldn't.

    So, I guess that puts us back where we started. As I have suggested before,,, looking at the specs for your pump,,, I don't see why , if all is running right why either wouldn't work great. Beyond that I can't give you any more insight.

    Tony
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