heat pump. 1 ton or 3 ton

Skippy · February 2013

A while ago, I installed my 3 ton heat pump, with a 40 gallon storage tank - to heat my house. It is a water to water system

I noticed that on really cold days (-20) - the heat pump would be coming on every 20 minutes, like clockwork. So that got me thinking, that if the three ton (3600 btu) heat pump comes on every 20 minutes, then (60 minutes divided by 3 = 20 - - - 3600 btu divided by 3 = 1200 or) a 1 ton heat pump would do the job running continuously. So when the weather is warmer, I would have a smaller heat pump running, with a smaller start up surge. When it gets REALLY cold, the 1 ton would run non-stop, but it WOULD heat the house.

What do you guys think ? Should I make the switch from the 3600 btu unit (3 ton) to the 1200 btu unit (1 ton) ?

The one 1200 btu unit I have heard about runs off 120 V, so I would not have to worry about 240 V wiring either . .

Then I would have to size my solar to run just the heat pump 24/7

westbranch · February 2013

Re: heat pump. 1 ton or 3 ton

I see what you are thinking of, first do the math, second you probably want to look at a 1.5 or 2 ton model to compare to so it has some room for colder weather... good luck...

Skippy · February 2013

Re: heat pump. 1 ton or 3 ton

I have also been looking at a woodstove or some other "back up" heat source, that is why I am looking at the 1 ton. . . it would do the job for 97 percent of the year . .

inetdog · February 2013

Re: heat pump. 1 ton or 3 ton

Skippy wrote: »

the heat pump would be coming on every 20 minutes, like clockwork. ?

The one 1200 btu unit I have heard about runs off 120 V, so I would not have to worry about 240 V wiring either . .

Then I would have to size my solar to run just the heat pump 24/7

1. The heat pump coming on every 20 minutes does not mean it is running only 1/3 of the time. The question is how long it keeps running each time it starts and how long it stays off.
Coming on every 20 minutes and running for 5 minutes would 1/4 time, coming on every 20 minutes and running 10 minutes would be 1/2 time.

2. Make sure you do not end up letting the temperature drop below the set point on your controls where the auxiliary heating kicks in (if you have it).

3. Not sure what the implications of running the compressor and water pumps continuously might be, but the 1 ton unit will at best last 1/3 as long as the 3 ton unit. (Unless starting is a large part of the wear on the components.)

4. The more you can run the heat pump during those daylight hours when the panels are producing, storing heat up for the night while at the same time charging the batteries, the less load you will be putting on the batteries. Running the heat pump around the clock, either with 1/3 or 1/1 duty cycle, will be hard on your batteries.
Compared to other parts of the system more panels are relatively cheap as long as you have a place to put them.

Skippy · February 2013

Re: heat pump. 1 ton or 3 ton

inetdog wrote: »

1. The heat pump coming on every 20 minutes does not mean it is running only 1/3 of the time. The question is how long it keeps running each time it starts and how long it stays off.
Coming on every 20 minutes and running for 5 minutes would 1/4 time, coming on every 20 minutes and running 10 minutes would be 1/2 time.

A - - This is actual run time, when I hear it running in the basement, it has a very low hum . . on 20 off 40 . . on 20 off 40 ...

2. Make sure you do not end up letting the temperature drop below the set point on your controls where the auxiliary heating kicks in (if you have it).

A - - no back up elements, I do have a de-superheater installed but do not use it.

3. Not sure what the implications of running the compressor and water pumps continuously might be, but the 1 ton unit will at best last 1/3 as long as the 3 ton unit. (Unless starting is a large part of the wear on the components.)

A - - I have a friend who put in a 4 ton unit the same time I put in my unit. He has a VERY drafty house - so his unit was running 24/7 - a week straight at least once a year - after 3 years, the main circut board in his heat pump burned out and had to be replaced. Was it a fault in the board, or was it overworked ?

4. The more you can run the heat pump during those daylight hours when the panels are producing, storing heat up for the night while at the same time charging the batteries, the less load you will be putting on the batteries. Running the heat pump around the clock, either with 1/3 or 1/1 duty cycle, will be hard on your batteries.

A - - I kinda figured that, may not be fesible to run heat pump off solar, but it would be nice to have a solar heated house. . .

Compared to other parts of the system more panels are relatively cheap as long as you have a place to put them.

Do you know that if you do all your typing in the "quote" area, it won't let you post it - the message is too short

;)

inetdog · February 2013

Re: heat pump. 1 ton or 3 ton

Skippy wrote: »

Do you know that if you do all your typing in the "quote" area, it won't let you post it - the message is too short ;)
Yes, I have noticed that. A real pain.
Wait a minute.... How did he do that?

Don't look at the man behind the curtain!

BB. · February 2013

Re: heat pump. 1 ton or 3 ton

Inetdog--You DOG. You know what you did. I have to watch for that when looking for spammers--Have not seen that for a couple years or so now.

-Bill

solarvic · February 2013

Re: heat pump. 1 ton or 3 ton

You didn,t say where you was circulating the water from. Are you circulatng water from a well or a pond to get the heat from? I know someone that gets thier water from a well for thier heatpump and dumps the water in a creek. My daughter circulates water thru a slinky that collects heat from the ground. At one time I was thinking of using my well for a heatpump but abandoned the idea when I had the gaswell drilled on my property so I don,t have any gas bell. :cool:solarvic:cool:

thehardway · February 2013

Re: heat pump. 1 ton or 3 ton

Skippy wrote: »

A while ago, I installed my 3 ton heat pump, with a 40 gallon storage tank - to heat my house. It is a water to water system

I noticed that on really cold days (-20) - the heat pump would be coming on every 20 minutes, like clockwork. So that got me thinking, that if the three ton (3600 btu) heat pump comes on every 20 minutes, then (60 minutes divided by 3 = 20 - - - 3600 btu divided by 3 = 1200 or) a 1 ton heat pump would do the job running continuously. So when the weather is warmer, I would have a smaller heat pump running, with a smaller start up surge. When it gets REALLY cold, the 1 ton would run non-stop, but it WOULD heat the house. What do you guys think ? Should I make the switch from the 3600 btu unit (3 ton) to the 1200 btu unit (1 ton) ?

The one 1200 btu unit I have heard about runs off 120 V, so I would not have to worry about 240 V wiring either . .

Then I would have to size my solar to run just the heat pump 24/7

First let me make one correction which I assume was a mistake. 1 ton = 12,000 btu not 1200. Think you just dropped a zero.

I have a 1 ton(12,000btu)LG ductless mini-split. It is an air/air unit. It runs on 120V and pulls 14.4A at compressor startup. The inside unit fan is 24VDC and runs of the same 120V feed via a transformer in the outdoor unit. This unit heats and cools my entire home quite well although the coldest nightime temps we have seen is 14 F. I plan to bring my ET solar collector system online this spring which next winter will heat the house via radiant floors and the 1 ton HP will be backup.

I get what you are trying to accomplish, but ahve a couple concerns. My First concern would be the effect continuous running would have on the lifespan of the unit. I would probably set it up as a two stage system. 1ton would be first system and operate within a specific operating range of outdoor temps cycling as normal. Stage 2 would be the 3 ton to handling only the extremes. They would back each other up.

Since you are talking about sizing a system, and heat pumps run all night as well as during the day, I am assuming you are planning on a battery bank. So you are talking about being able to save $ by down sizing the inverter correct? Batteries would be somewhat agnostic as to whether load was in short peak or continuous run. Take some measurements and see what your peak load on the 240V 3 ton unit is at start-up and at run. 240V equipment is usually more efficient when running than 120V so it may not save as much as you think. You may be able to limit start up peak using a soft start or a capacitor. If that's not possible, perhaps 2(qty) --1Ton 120V units, staged with offset start-ups would be the ticket. Allows you to run one unit majority of the year but gives you additional capacity during extreme cold and a backup unit to boot.

solarvic · February 2013

Re: heat pump. 1 ton or 3 ton

Does your water to water heat pump also have electric heating elements? If the 1 ton can,t get enough heat from the water it will run the heating elements. That will need a lot more electric to heat with the heating elements than you would probably need with the 3 ton heat pump. solarvic

Skippy · February 2013

Re: heat pump. 1 ton or 3 ton

Skippy wrote: »

Do you know that if you do all your typing in the "quote" area, it won't let you post it - the message is too short ;)

How did he do that ? ? ?

Don't look at the man behind the curtain!

Put your pants back on !

Skippy · February 2013

Re: heat pump. 1 ton or 3 ton

solarvic wrote: »

You didn,t say where you was circulating the water from. Are you circulatng water from a well or a pond to get the heat from? I know someone that gets thier water from a well for thier heatpump and dumps the water in a creek. My daughter circulates water thru a slinky that collects heat from the ground. At one time I was thinking of using my well for a heatpump but abandoned the idea when I had the gaswell drilled on my property so I don,t have any gas bell. :cool:solarvic:cool:

I had the back hoe come in and dig 3 - 60 foot trenches 10 feet wide in my back yard and install horizontal plastic piping . . the general rule of thumb is 600 feet per ton, but when they installed my system, he noticed it was dry gravely - sand, so he threw in another 600 feet while he was at it. So on a 3 ton unit, I have 2,400 feet of pipe, and it circulates a glycol solution thru that.... its worked great so far. . .

Skippy · February 2013

Re: heat pump. 1 ton or 3 ton

thehardway wrote: »

First let me make one correction which I assume was a mistake. 1 ton = 12,000 btu not 1200. Think you just dropped a zero.

I have a 1 ton(12,000btu)LG ductless mini-split. It is an air/air unit. It runs on 120V and pulls 14.4A at compressor startup. The inside unit fan is 24VDC and runs of the same 120V feed via a transformer in the outdoor unit. This unit heats and cools my entire home quite well although the coldest nightime temps we have seen is 14 F. I plan to bring my ET solar collector system online this spring which next winter will heat the house via radiant floors and the 1 ton HP will be backup.

I get what you are trying to accomplish, but ahve a couple concerns. My First concern would be the effect continuous running would have on the lifespan of the unit. I would probably set it up as a two stage system. 1ton would be first system and operate within a specific operating range of outdoor temps cycling as normal. Stage 2 would be the 3 ton to handling only the extremes. They would back each other up.

Since you are talking about sizing a system, and heat pumps run all night as well as during the day, I am assuming you are planning on a battery bank. So you are talking about being able to save $ by down sizing the inverter correct? Batteries would be somewhat agnostic as to whether load was in short peak or continuous run. Take some measurements and see what your peak load on the 240V 3 ton unit is at start-up and at run. 240V equipment is usually more efficient when running than 120V so it may not save as much as you think. You may be able to limit start up peak using a soft start or a capacitor. If that's not possible, perhaps 2(qty) --1Ton 120V units, staged with offset start-ups would be the ticket. Allows you to run one unit majority of the year but gives you additional capacity during extreme cold and a backup unit to boot.

You are right about that one ! It is 12,000 btu per ton, or 36,000 btu for the 3 ton . . . easy to drop a 0 .

I was a bit concerned with the outdoor air temp, that is why I went with a water-water, when its -20 C or -4 F outside, the air-air would have to w.ork too hard . .

I would have to agree with you on the continuous running, as I stated in one of my posts, my buddies system has run non-stop for at least 1 week a year, and after 3 or 4 years, the main circut board went out. . . But, with global warming, those kinds of temperatures are getting fewer and farther between. . . so far this year, its only gone down to 5 F or -15 C, and that was only for 3 days. . . not a full week.

I have no way of measuring the loads put on my heat pump, and not even sure if I can find a 1 ton unit to - play with. . . so I will wait to see if somebody out there can find me a 1 ton w-w boiler. . . I have had no luck.
Don't forget, if the 1 ton unit does run too much, I have the option of turning on a space heater (or getting a wood stove) - I have been worried about having an all electric house, when the power goes out - I'm in trouble .

So if anybody out there wants to keep an eye out for a 1 ton w-w heat pump, or has a heat pump installed, and would like to do some power consumption readings, that would be great !

solarvic · February 2013

Re: heat pump. 1 ton or 3 ton

My daughter lives across the road from me and has a 3 ton heat pump. I call it a defective cheap install. I am located 50 miles south of Ere so probably have similar temp as you. In January they used 4500 kwh. Steve got a ted to monitor the use of the electric so he can prove his case if he has to sue them. Ted showed that the heat strips were supplying the heat. The problem is they didn,t bury the slinky right or deep enoughand not enough pipe in first place. They only dug the hole about 5 feet deep with a small excavator with about a 30 inch bucket. Instead of laying the slinky flat they stood it up n end. I have a friend that has installed some of them and says they always go at least 5 ft. deep and lay the slinkys flat. I think accotding to osha regulations you aren,t suposed to have a trench more than 5 ft.deep without cave in protection. If the backhole guy does his job right you don,t have to even get into the ditch. You should be happy that your installer put in the extra pipe and stay with your heatpump. What brand do you have? If I didn,t have my free gas I would probably put in a heatpump, Probably a water furnace. Wet ground is a good place for the slinky and my back yard is a swamp. solarvic If you are worried about a power outage you could get an unvented heater for emergency. Here I have electric for a backup in case my gaswell goes down. So far my gaswell never went down. :Dsolarvic:D

Skippy · February 2013

Re: heat pump. 1 ton or 3 ton

solarvic wrote: »

My daughter lives across the road from me and has a 3 ton heat pump. I call it a defective cheap install. I am located 50 miles south of Ere so probably have similar temp as you. In January they used 4500 kwh. Steve got a ted to monitor the use of the electric so he can prove his case if he has to sue them. Ted showed that the heat strips were supplying the heat. The problem is they didn,t bury the slinky right or deep enoughand not enough pipe in first place. They only dug the hole about 5 feet deep with a small excavator with about a 30 inch bucket. Instead of laying the slinky flat they stood it up n end. I have a friend that has installed some of them and says they always go at least 5 ft. deep and lay the slinkys flat. I think accotding to osha regulations you aren,t suposed to have a trench more than 5 ft.deep without cave in protection. If the backhole guy does his job right you don,t have to even get into the ditch. You should be happy that your installer put in the extra pipe and stay with your heatpump. What brand do you have? If I didn,t have my free gas I would probably put in a heatpump, Probably a water furnace. Wet ground is a good place for the slinky and my back yard is a swamp. solarvic If you are worried about a power outage you could get an unvented heater for emergency. Here I have electric for a backup in case my gaswell goes down. So far my gaswell never went down. :Dsolarvic:D

Your not alone with "cheapie" installs. I know of 2 cases in my home town, where the installer told them they can run the system on 200 or 300 feet of tubing per ton. What ends up happening, is the pipe gets super cold (since the glycol will not freeze) it turns the ground around the pipe into one big round ice cube, and when spring comes, it melts, and collapses into a trench (mud) - exactly where the pipe is buried. The one guy that showed me his back yard has a trench that if you stand in the bottom, and bend your other knee at 90 degrees - is how deep the trench is - he is peeeved ! and ready to sue to.... and he has back filled the thing 3 times !

Like I said in the "cost of hydro" thread, heat-hydro-hot water for me is around 700 kwh for the month. I think the highest I have ever had since putting in the combo of heat pump for house heat, and on demand for water heat - wouldn't be over 1,000 kwh.

My unit is a water furnace, but its the smallest unit they make. I am currently trying to get a hold of a different maker to see if they even make a 1 ton.

I would classify "my guy" as pretty good, by my experience with him - that said, he has told me of situations where he has been called in to fix a "problem", and people have installed -entire home heating "loops" in an area of about 20 feet square . . he laughs when he says he has to take a jack - hammer to the ice block it makes.

When it comes to heat pumps, more pipe is better, AND the wetter the better. If you have a river going by your house - perfect ! drop the loop in the water. Just weight it down so it don't float.

thehardway · February 2013

Re: heat pump. 1 ton or 3 ton

Skippy,

I am sitting here at my desk right now looking at a 1T water/water GHP.

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It was given to me by a kind elderly gentleman who is a firm believer in GHP's and he said this is a well made unit. The name on the manual is Creative Power. It reportedly uses a Sanyo compressor.
It is made in China which I'm not crazy about but that said I imagine most of the other units are as well or at least a major portion of their components even though they claim US. I was told it is available direct from manufacturer but I cannot find the model number (CRS4e/R) on their website.

http://en.cn-xny.com.cn/about/&FrontComContent_list01-1282546591785ContId=8d7ccc42-d108-4430-8af8-434efa82efd8&comContentId=8d7ccc42-d108-4430-8af8-434efa82efd8&comp_stats=comp-FrontComContent_list01-1282546591785.html

I am in no way endorsing this company. As far as I am concerned the product they produce is yet to be evaluated and I only offered it as several members have asked for sourcing info.

This said, by the time you purchase your smaller heat pump and install it, you may well have paid for the cost of the larger inverter and the larger inverter may come in handy down the road. Other than the cycling you are experiencing a few days out of the year, you sound fairly happy so I would say just supplement on cold days with a woodstove or a LP fireplace and stick with the 3 ton, at least you and your pipes will not freeze in a power outage that way.

You were right to go W2W on it for your climate. Our temps in VA don't get anywhere near as low as yours. I only offered my unit as a benchmark that a 1T unit is capable of heating a well insulated home.

I have found that most manufacturers over spec the max A. draw on there units for a worst case scenario and you seldom see that in real life operation, that's why I said take an actual reading. You should be able to do this at your electrical panel using an basic clamp around style ammeter. Once you know your start-up electrical load and your continuous load you will have a better reference. Hopefully you can read the spec picture I took on the 1T w/w GSHP I have. I do not know actual loads or performance yet but will post it when I do.

Blackcherry04 · February 2013

Re: heat pump. 1 ton or 3 ton

Check all the Marine Heat Pump / Air Conditioning Manufacturers, they all make water / water or water / air units. You may find a water / air unit with it's output in your duct system ( if you have one ) is a better option to get distribution of it's output. I have 5 units ( 5,000 btu -16,000 btu ) on my boat all zoned in different areas. A Boat is long and can have all kinds of varying heat loads front to rear. Staging is another good option. I have a supplemental system with a 40 gal hot water heater I can use to pre-warm in a emergency or shift the output to a air coil in the duct system.

Skippy · February 2013

Re: heat pump. 1 ton or 3 ton

thehardway wrote: »

Skippy,

I am sitting here at my desk right now looking at a 1T water/water GHP.

Its good to know they are being made. Thanks for the info. I will have to check out the marine places as well.. . who knows, I may be able to find a 1.5 ton . . . still thinking about it. It doesn't hurt to wait and ask questions. . ..

Sulfur · March 2013

Re: heat pump. 1 ton or 3 ton

Skippy wrote: »

A while ago, I installed my 3 ton heat pump, with a 40 gallon storage tank - to heat my house. It is a water to water system

I noticed that on really cold days (-20) - the heat pump would be coming on every 20 minutes, like clockwork. So that got me thinking, that if the three ton (3600 btu) heat pump comes on every 20 minutes, then (60 minutes divided by 3 = 20 - - - 3600 btu divided by 3 = 1200 or) a 1 ton heat pump would do the job running continuously. So when the weather is warmer, I would have a smaller heat pump running, with a smaller start up surge. When it gets REALLY cold, the 1 ton would run non-stop, but it WOULD heat the house.

What do you guys think ? Should I make the switch from the 3600 btu unit (3 ton) to the 1200 btu unit (1 ton) ?

The one 1200 btu unit I have heard about runs off 120 V, so I would not have to worry about 240 V wiring either . .

Then I would have to size my solar to run just the heat pump 24/7

How often your heat pump comes on per hour is not relevant, for this analysis you would need to measure how long it runs per hour on the coldest night of the year (or close to it). what are you exchanging heat with now? you say it is water to water. The 40 gallon storage tank you mention, is that for the desuperheater to preheat water before it goes to your hot water heater?

There should be a jumper to disable the electric heating element in your heat pump exit ducting, make sure to disable this or it will come on and use a lot of power if the thermostat is several degrees from setpoint. You probably don't want that to come one unless you know about it.

my heat pump is 4 ton Water Furnace geothermal with vertical ground loops.

do you have a coil with a fan outside? if so, then it is an air source heat pump. if you already have geothermal heat pump, why would you replace it? what advantage would there be?

LucMan · March 2013

Re: heat pump. 1 ton or 3 ton

Skippy wrote: »

A while ago, I installed my 3 ton heat pump, with a 40 gallon storage tank - to heat my house. It is a water to water system

I noticed that on really cold days (-20) - the heat pump would be coming on every 20 minutes, like clockwork. So that got me thinking, that if the three ton (3600 btu) heat pump comes on every 20 minutes, then (60 minutes divided by 3 = 20 - - - 3600 btu divided by 3 = 1200 or) a 1 ton heat pump would do the job running continuously. So when the weather is warmer, I would have a smaller heat pump running, with a smaller start up surge. When it gets REALLY cold, the 1 ton would run non-stop, but it WOULD heat the house.

What do you guys think ? Should I make the switch from the 3600 btu unit (3 ton) to the 1200 btu unit (1 ton) ?

The one 1200 btu unit I have heard about runs off 120 V, so I would not have to worry about 240 V wiring either . .

Then I would have to size my solar to run just the heat pump 24/7

Your heat pump needs to be sized according to the BTU heat loss at the lowest expected outdoor temperature for your climate. The ground temperature drops throughout the heating season as the heat is transferred into your home through the heatpump. The ground temp maybe 55 degrees in October and 25 degrees in January after running your heatpump, depending on the size of your ground loop. As the ground temperature decreases the BTU capacity of your heatpump will also decrease as it is proportional to the ground loop temperature.
So before making any changes you will need to know what your homes BTU heatloss is at the lowest projected temperature during the heating season and that will determine the size heatpump required. A 1 ton heatpump most likely will be sufficient for a 400-600 sq ft home unless less the house is extremely well insulated.

Skippy · March 2013

Re: heat pump. 1 ton or 3 ton

LucMan wrote: »

Your heat pump needs to be sized according to the BTU heat loss at the lowest expected outdoor temperature for your climate. The ground temperature drops throughout the heating season . . .

That is a good point, as the ground cools off, it has to work harder. . . . so it's nice that I have the extra 600 feet of tubing underground (over sized ground loop). . also, at the time of the heat pump coming on for 20 min every hour, it was late in the heating season (mid Feb.) and it was -20 outside - the coldest I have seen it yet . . so looking at the numbers, a 1 ton running continuous should do the same job as the 3 ton running 20 min. out of every 60 . . . in theory. .:p

heat pump. 1 ton or 3 ton

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