Generator Block Heater

Mangas

Our new Cummins Onan RS20000 propane generator is equipped with a block heater.

We set up a hardwired a 110v receptacle inside the unit for the trickle charger and block heater. I plan to plug a 24/7 programmable digital timer into the receptacle for the heater but am not sure where my set points should be nor when I need to plug the heater into the programmer.

My plan is to program the heater to start at 9 PM and shut off at say 9 AM to maximize battery charging capacity during the day. The 1,500 watt heater draws about 10 amps and has a thermostat to maintain a constant block temperature.

Also, I am not sure when I need it. I think when the ambient air temp is going to be below 32 degrees is probably a good guideline but the generator guys told me propane units are not as finicky as gas/diesel gennys and they have seen propane units fire right up at 17 degrees with no problems.

Of course the warmer the block the less war and tear on the mechanicals.

What do you guys think? My plan ok?

Ralph Day

Re: Generator Block Heater

How often does the genset run? Are you always around (I think so if I remember your previous info)? Do you have any spare wires running from your house to the genset location?

The questions are asked because 1)If you run every day then sure, sacrifice the power to heat the block. 2) if you're always around then you can just goose the heater for 30 minutes or so before you start it up (if you don't run things on auto) and 3) if you're like me and don't want to go out in the cold and snow if you don'tneed to, and you have some power wires running to the genset you could set up a clock type timer (like for a bathroom fan, but 1500 watt capacity) and just do your 30 minute warm up from the comfort of your control room.

I had an extra 12/2 wire between house and gen shed unused, put it on the block heater with the timer switch in the house...crank it, wait 30 then fire up the genset. The timer switch keeps you from leaving the heater running for too long when not needed. Old electricians rule told to me...if you can, pull at least one extra wire if you're pulling wire.

BTW, after 1 charge or exercising run I check the oil and coolant levels before the next run...just in case.

Ralph

sawmill

Re: Generator Block Heater

I can't imagine a gas (or diesel) engine that would need a block heater at 32 degrees or even down to 20. With the good quality oils available today and their multi-viscosity and coating ability, pre-heating the block would add very little to the lube factor. If this was a concern an electric pre-lube pump operated for a few seconds before starting would be of more benefit than warming the block.

Every day in the US there are millions of gas engines started without block heaters. It is quite common to find many gas vehicles with an excess of 200k miles.

If correct? I believe your genset uses a 4 cyl Ford engine with a 325 CCA battery. For reliable cold weather starting 750 CCAs or more would be a necessity. A 325 CCA is a light duty warm weather battery more suited to riding lawnmowers than any type of industrial use.

On my diesel equipment, I only use the block heater at 20 degrees or less and for a period of two hours before starting. A Case (gas) tractor in excess of 50 years old with no type of heater and has never failed to start. This is where the CCAs show their importance. By the way just about everything is wore out on the Case except the engine, so pre-heating has not been a factor for it's engine life.

For stand by use a float charger would be better than a trickle one. My experience with trickle chargers has been they will eventually cause acid loss.

Not offering advice just my experience from the school of hard knocks.

mike95490

Re: Generator Block Heater

Bad idea.

If you need to crank up the genset, it means the batteries are low, and hooking up a 10A AC load (uh oh - here's the bad part) that's 1500 watt load, and your inverter is going to pull close to 1800 watts from the weak batteries. Figure 30 minutes to heat, and that's a boatload of power. If it's propane, you should be fine without it.

How cold does it get in your area ? How often do you plan on running genset?

I'd look into super insulating it, so it stays warm from the previous run.

Ralph Day

Re: Generator Block Heater

I always factor in the block heater draw as part of the discharge before operation. ie don't realize you're at 30%SOC, then you need to drain batteries even further to get the charge going. Unless you have extravagent power using visitors or a load left on by mistake you get to know your system and when you need to use your fossil fuel generation. (at least in my case, how about the rest of you?)

Ralph

Cariboocoot

Re: Generator Block Heater

A block heater in an emergency back-up power gen set? Brilliant. When there's no power because of the ice storm you can ... do nothing.

I've started gasoline engines without block heaters at -40. They're not happy about it and you need the starting battery to be good, but it will work. Diesels won't, usually because the fuel congeals at low temps. You can buy a winter additive for them.

Propane will have a similar problem to the diesel; the liquid fuel will not be keen on vaporizing. But it will work. My advice is keep the battery charged automatically and don't worry about the block heater. It's a waste of power. A propane torch can be used to heat the cylinder head if things get really bad.

Remember I live where -40 is a normal Winter temp.

BB.

Re: Generator Block Heater

Remember, he has a very large off grid system. Running a block heater for 3 hours is not much of a load for his system.

Although, I do like the idea of an insulated enclosure plus, perhaps a propane space heater, for warming when needed.

-Bill

Mangas

Re: Generator Block Heater

Thanks guys.

The genset only runs about 60 - 80 hours a year, including exercise, mostly in winter and the August summer rain period. The genset is in an enclosed weathertight cover.

The off grid system easily handles the 1,500 w load (note signature). I had the thermostatically controlled heater on all last night through this evening after 2 days of very overcast weather with night time temps down in the mid 20s. Normally here in S.E. Arizona our winters deliver about 20% overcast/PC skies with daytime temps of 50 degrees down to 15 - 35 degrees at night.

Boot, I'm off grid. -40 degrees is "normal". . .?

The house's two furnace air handlers ran all night along with normal house draws and the battery voltages were still fine this morning. The inverters are programmed to automatically start the genset if battery voltages get too low. They didn't need to turn the genset on to boot the batteries. The new Trojan REBs' are performing much better than the older version both from a capacity as well as water consumption standpoint.

You answered what I needed to know i.e. the genset doesn't need a blanket unless we get very cold, say below "0" degrees. I am probably being overly cautious but my reasoning was during cold overcast periods if the genset is warm it will power up and deliver voltage more efficiently to the inverters especially during the first 10 minutes into its programmed 2 hour run time.

My previous Generac lost its mechanical actuator type governor during a cold spell (rare "0" degree weather) and failed. The Onan doesn't use a mechanical one.

After a cold wet day on horseback, I sure don't plan to get up in the middle of the night to check battery voltages and plug it in!

westbranch

Re: Generator Block Heater

Mangas, I live just a bit north of the old "Coot" and have had my share of 'COLD' (-40) Cariboo/Chilcotin winters over the last 40 years... ie formerly soft truck seats are hard as a 2x4, transmissions that resist coming out of gear without superhuman effort... an engine that truly groans when you try to turn it over...even with 5W oil in the pan.

After those temps you feel like wearing a T shirt when it gets to - 18/ 0 F...

If your are really worried about the diesel genset starting in temps INSIDE your gen house that are below 15F you might want to investigate propane block heaters. The Highways dept uses them on the graders that get parked overnight on the side of the rural roads here and they always start... unless there was a mechanical issue.

They do have to use WINTER grade diesel. you can only buy it after October in this area. The temp rating drops from -10 C to - 30C then backup to -10 during the winter months. 'Summer ' grade is usually good to - 10 in an outdoor application with a FULLY charged battery. My 92 JD backhoe starts easily to -10C/15F, after that no go without using the block heater.

The problem is 'gelling ' of the waxes in summer grade fuel.

lots of links, strangely most in Canada(???) must be cold up here or something? eh?

eg http://www.powertogo.ca/engine_heaters.htm

Alternatively you might rig up an electric block heater that kicks in at ~ 20 F as the temps drop or a propane space heater in the gen house. Also you will need to heat the fuel tank to minimize fuel gelling if it is outside and you have summer fuel.

HTH
Eric

waynefromnscanada

Re: Generator Block Heater

Something else to consider in the extreme cold is 0W30 motor oil. In the cold, it never gets thicker than 0W, and when hot, it never gets thinner than 30W. Been using it for decades in my vehicles during Winter and starting is very noticeably easier. Also the 0W30 gets flowing quicker to lub those critical engine parts after cold starts when most engine wear normally takes place as oil pumps try to push cold molasses through the engine. In fact, for these and other reasons, Toyota, starting with most of their 2011 models, "will be factory filling and certified exclusively for use with 0W20 motor oil", as well as recommending it for most of their models built since 2000. Motor oils have indeed come a long, long way over the years.

stephendv

Re: Generator Block Heater

The problem I see with a timer is that you may be heating the block every night, even if you're not going to be using the generator the next morning. What about connecting the heater inline with the starting system of the generator, so that it has a long pre-warm time before cranking?

Mangas

Re: Generator Block Heater

You guys living in the really cold areas know a lot more about this than I do having experience with the operating mechanicals in truly frigid temps. At -40, I must look pretty sorry to you worrying about a paltry 15 - 25 degress. I run 10w 30 in winter which for our location does pretty well except for my heavy equipment which I use 15 w 40 w.

Our inverters are programmed to run the genset only when the battery voltages get infrequently low during extended periods of cold incelement weather. This happens when the furnace air handlers are cycling/running a lot to keep the house warm (propane furnaces) and charging can't keep up. When it happens it mostly does so in the early morning hours.

Like you guys said, I probably don't need to warm the genset up unless I'm running south of "0". If we get consecutive days of below "0" overcast weather at night, I think I'll program the timer to come on at say 2 AM and shut off at 6 AM until the weather clears. We're off grid so there is no power consumption cost running the heater as it doesn't draw enough to significantly impact battery voltage parameters. What I worry about is the inverters sensing a slow genset start and voltage loss in frigid weather thereby shutting the genset down.

What would be interesting is to have an outside air temp sensor line running back inside to the inverters with another sensor line from the inverters back outside to my switched A/C plug receptacle inside the genset. If battery voltages got near the threshold where the inverters were nearing the genset start point and the inverters also sensed outside temperatures below a certain temperature the inverters would signal the heater timer plugged into the receptacle to come on for 1 to 2 programmed hours.

Probably too complicated but that's the operting parameter.

mike95490

Re: Generator Block Heater

no power consumption cost running the heater as it doesn't draw enough to significantly impact battery voltage parameters.
64xTrojan L16-REB 6v

OMG ! 8 parallel strings of 400ah batteries 3200ah @ 48V

But it does add to the cycle count toward replacement.

Mangas

Re: Generator Block Heater

Hi Mike,

I missed that one.

You're absolutely right about the battery cycle count. Hadn't thought about that.
All the more reason I'll be selective when I use it under severe conditions.

Our system really is a beast.

westbranch

Re: Generator Block Heater

Mangas, I just remembered that there are what we have called "heater tapes" a power cord that is used to keep waterlines from freezing. they work by having a built in sensor that closes the circuit at around freezing. there is also a version that will control your block heater, apparently made by Woods.

an example

http://www.canadiantire.ca/AST/browse/HouseofInnovation/House-Home/PRD~0522463P/NOMA+Block+Heater+Cord.jsp?locale=en

oil pan heater
http://www.canadiantire.ca/AST/browse/4/Auto/Winter-Driving/WinterAutomotive/PRD~0303203P/ZeroStart+Super+Heat+Magnet.jsp?locale=en

HTH

Mangas

Re: Generator Block Heater

Thank you Westbranch!

That's the best idea I've seen yet i.e. a combination on/off time duration programmer and temp sensor which I can interface to the heater cord. If I read it right you can also program at what temp it turns the timer on and off.

I'm going to give them a call tomorrow.

westbranch

Re: Generator Block Heater

Another option, warm the oil pan

http://www.wolverineheater.com/

Ralph Day

Re: Generator Block Heater

Also you can get block heater sensors...you plug your load into the socket, the socket is plugged into an outlet and the block heater will come on only when the temp gets below the designed setpoint. That with a timer was what I covered my school bus with for many years.

http://www.usfreedombiofuels.com/engine%20heaters/thermal-cubes.html

There are various manufacturers with different temperature setpoints.

Ralph

mike95490

Re: Generator Block Heater

I sure like that idea of a propane fired heater, as I think it's a propane genset too ??

chevenstein

Re: Generator Block Heater

For what it's worth, I get some -20F winter weather where I am and have been able to consistently start my propane genset in this weather with no trouble using no starting aids. I run synthetic 5W30 in it and it starts when it's 20 below the same as if it were summer time. As previously mentioned, cranking amps are key, as is the quality of the battery electrical connections (just as with our inverter to battery connections).

On the LP vaporization issue, there are charts relating LP vaporization rates (usually in BTUs) to temperature; plug your temp and load into the chart and you'll get an idea of whether your tank is big enough.

Edit: Here's a good chart for larger tanks. Note that the vapor pressure decreases with the amount of fuel left in the tank, too: http://www.hytopz.com/sales/products.asp?cid=1334

Mangas

Re: Generator Block Heater

Thanks Ralph, I'll take a look at that one too.

After reading everyone's assurances I feel more confident about the cold weather starts. We have it hooked up to an underground 500 gal propane storage tank. The in line heater on the unit is a thermostatically controlled coolant recirc type.

I was most concerned about those first 5 minutes of run time when the genset is interfacing with the inverters. My feeling right or wrong was keeping the genset warm overnight when it might be called upon to boot the batteries would reduce the risk of the inverters shutting it down if there were voltage fluctuations during the cold start.

I've always been a "hand wringer" when it come to managing our off grid system. I had some very bad and costly experiences with our previous Generac genset which I got rid of this year. Never again.

Hearing about those temps you guys up North deal with, I've got my tail between my legs.

icarus

Re: Generator Block Heater

Personally, I think you are finding a solution in search of a problem. I wouldn't worry about block heating unless the temps were consistently below ~ +10F. That said, I would get a coolant heater that is fueled by propane. I know that Webasto and Espar make diesel fueled coolant heaters (designed to preheat engines and provide sleeper or cabin heat for transport trucks.) I can't imagine that that there are not propane powered units that do the same thing. (see links below!)

On the simpler solutions, we have used Zodi tent heaters to fan force duct heat to small engines safely to help cold starts. I also would consider using engine oil sump heaters instead, as heating the oil pan well helps cold starts as well as coolant heat, but provides better cold start lube.

A quick google search shows these:

http://www.enviroharvest.ca/block_heater.htm
http://www.engineblockheater.net/page1.html

techntrek

Re: Generator Block Heater

I frequent a Generac board, and the general conensus there by those that live in very cold climates is... forget the engine block heater, but use a battery warmer attached to a temperature-controlled outlet. The later can be bought all over the 'net.

wrdaigle

Re: Generator Block Heater

I have a Kohler propane unit with a built in carb heater. The unit has a hard time starting when temps drop below 0. 5 minutes with th carb heater plugged in and it starts every time. It only uses about 30 watts.

Mangas

Re: Generator Block Heater

Tested the set up last night. Heater came on at 9PM, furnace air handlers ran all night, genset fired right up without any stumble at 5 AM to boot the batteries and ran smoothly for its two hour program.

Expect 8 to 0 degree weather tomorrow morning.

Noticed the coolant recirc heater keeps the enclosure temperate overnight. The battery stays warm sitting a few inches form the heated block.

Thanks to everyone for their help and advice.