Random Questions on Heating

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Random Questions on Heating

October 16, 2021, 10:32:11 pm

With the weather starting to cool, I wanted to give the heaters a test, which prompted some questions.

1- I have 2 Dometic Penguins with heat pumps (uses electricity). Heat works on both. Are these good to use above freezing temps?

2- I then tried the furnaces (uses propane). Zone 1 (front) works fine the rear heater. Zone 2 did blew air but it was not warm. Where should I look to resolve this? Is there 1 propane heater, or are there 2?

3- I also have some 1500w Lasko space heaters, these work excellent. I would prefer to use electric over propane since it does not require refueling as often. Would it be more efficient to plug in 1-2 of these instead of either of the above?

Re: Random Questions on Heating

Reply #1 – October 16, 2021, 10:47:00 pm

Quote from: Jason – October 16, 2021, 10:32:11 pm

1- I have 2 Dometic Penguins with heat pumps (uses electricity).

2- I then tried the furnaces (uses propane). Is there 1 propane heater, or are there 2?

3- I also have some 1500w Lasko space heaters, these work excellent.

1. Your Penguin roof units may or may not be heat pumps. They made them both ways. You might have electric resistance heat coils in your A/C units. Either way, if you are plugged in to shore power, they would be OK in moderately cold conditions. Below about 40 degrees, heat pumps (in "heat" mode) become less efficient. Would just depend on your personal preference. Some members like running the roof units for heat - others prefer using other heat sources.

2. I don't know. Look on the outside walls of your coach. The propane furnaces have a outside exhaust outlet that blows very hot air when the heater is running. Do you have one exhaust outlet, or two?

3. Again, personal preference. In our coach, when we are plugged into shore power, we prefer using small thermostatically controlled space heaters for our primary heat source, and the propane heaters as backup. When dry camping or boondocking, of course, we rely on the propane heaters. If you DO have two propane heaters, note that the wet bay heat outlets only work when you are running the rear heater. We keep a small electric heater in each end of the wet bay all winter, with our propane furnaces turned on but set to the lowest "activation" temp (about 50 degrees). As long as we have shore power, the electric heaters keep everything thawed out. If we lose shore power, then the rear propane heater kicks on to take over.

Re: Random Questions on Heating

Reply #2 – October 16, 2021, 11:21:12 pm

I prefer electric floor heaters and in the winter when charging the batteries I run
2 electric heaters and flip the Aqua-Hot on electric so I put a load on the generator.
At home when it is freezing I have the Aqua-Hot on electric and one heater keeps
the coach warm enough so nothing freezes. I have never tried the heat pumps as
if I'm heating I want to do it on the floor and not from the ceiling.

Re: Random Questions on Heating

Reply #3 – October 16, 2021, 11:35:08 pm

If your AC is a heat pump, works best over 40 to 45 degrees outside temp. If heat strips should work at any outdoor temp.

On the small space heaters, I never run 2 of them on high setting at the same time. Lot's of amps on what may be one electric line/breaker.

When I had a propane heat coach, with no heat pump or strips in the ACs, I always ran either one space heater on high, or 2 on low setting.

Re: Random Questions on Heating

Reply #4 – October 16, 2021, 11:50:50 pm

This is for dry camping/boondocking where electricity will not be available.

Rear propane furnace should be repaired as not much goes wrong with them. The rear furnace can be noisy at night so we don't use it.

If you use an unvented/vent free propane heater inside, a catalytic type is the best choice as they don't produce much carbon monoxide and are very efficient. A window should still be opened a little so some efficiency is lost. Unvented heaters will raise the humidity inside the coach. Placement is important as they can easily start a fire if close to something combustible.

Gas heating is efficient and a coach propane tank will last a very long time. The OEM propane heaters do waste some energy out the exhaust.

Pierce

Re: Random Questions on Heating

Reply #5 – October 17, 2021, 07:18:49 am

We have 3 Heat Pumps on top and have run them down into 28 degree's with satisfactory results. Was always told they are not efficient below 36 degree's, but that is not the case! Always run the Electric with our Aqua Hot when parked. Always good to exercise both the Heat Pump option as well as the Air Conditioners during the year. Just like a diesel coach, not made to just sit!
I know this does not answer your question on your propane heater, but yes, you do need to find out what is going on with it. Pretty simple devices, but you don't want a leak in them.

Re: Random Questions on Heating

Reply #6 – October 17, 2021, 08:57:46 am

Quote from: Jason – October 16, 2021, 10:32:11 pm

Zone 1 (front) works fine. The rear heater (Zone 2) did blow air but it was not warm. Where should I look to resolve this?

Back to your original question, which has not been answered: Furnace blows cold air.

This is a classic failure mode for RV propane furnaces. You probably have Atwood Hydro-Flame models in your coach. If not, then other brands work pretty much the same.

Before the furnace will blow hot air, a specific series of events must transpire. Rather than list them all, I will refer you to Pg. 16 in the manual linked below. The most likely suspects for your problem are:
1. Dirty or faulty Sail Switch
2. Faulty Limit Switch
3. Faulty Circuit Board
4. Faulty Gas Solenoid Valve
5. Faulty Ignitor Electrode

All of these items can be replaced or repaired by the owner. Just depends on how mechanically inclined you are. Refer to Pg. 30 in the manual linked below. If in doubt, I recommend taking it to a qualified mechanic for service.

https://myrvworks.com/wp-content/uploads/2019/04/Atwood-Shop-Manual-HydroFlame.pdf

Re: Random Questions on Heating

Reply #7 – October 17, 2021, 09:12:00 am

Here is a simple test anyone can do to help narrow down the cause of "no heat" problem.

Find the physical location (inside the coach) of the problem heater. You want to get your ear as close to the heater as possible so you can HEAR what it is doing. While you listen to the heater, have your helper turn it on using the wall thermostat control.

First thing: You will hear the blower fan come on. IF this happens, you know you have good 12V power to the fan motor.

Next, after about 20-30 seconds, you should hear a distinct "CLICK" sound. This is the gas valve being told to open by the control circuit board. If you do not hear this "CLICK" then you either have a dirty or bad sail switch (EASY FIX) or a bad circuit board (EASY FIX) or you have a bad gas valve (NOT so easy fix).

If you hear the "CLICK" the next sound should be a WHOOSH noise of the gas being lit by the ignitor electrode. You should then hear the fire burning, and soon should get heat out of the heater outlets. If you don't hear the WHOOSH of the fire being ignited then it could (again) be a faulty circuit board (EASY FIX) OR it could be a bad ignitor electrode (MODERATELY easy fix).

If the fire doesn't light, with the original OEM circuit board, the blower fan will continue to run blowing cold air until you cycle the furnace OFF and back ON with the wall control.

If you decide to replace the circuit board, you should buy the upgraded model from Dinosaur. It is greatly superior to the old OEM board.

Ignitor Board Index page

Re: Random Questions on Heating

Reply #8 – October 17, 2021, 09:19:14 am

Another cause of the sail switch not closing which means the gas valve doesn't open and ignitor doesn't fire is restricted air flow.

Verify that all heater vents are open and ducts not crushed or crimped. Also, that the return/intake side of the furnace is not restricted.

Re: Random Questions on Heating

Reply #9 – October 17, 2021, 10:12:16 am

Irregardless of what your heating source is, I recommend you place a small fan up near the ceiling to cause air circulation that would then prevent the heat stratification up by the ceiling.
Saves a lot of fuel by doing this, as it can get quite cold down by the floor and very warm up near the ceiling where nobody is.
I actually rigged up an old 120V heater fan to blow the warm ceiling air from the cockpit area all the way back to the bedroom. It works great and we didn't have any cold areas. This way we didn't have to use the rear furnace at night. We also opened all our cupboards and cabinets at night so nothing would freeze. This was all done in our 1989 GV that was not a "designed for winter coach" and the temps outside got down in to the teens.

Re: Random Questions on Heating

Reply #10 – October 17, 2021, 05:57:08 pm

To answer one of the original questions, you have two furnaces. See Foretravel Motorhome 2000 U295 Specifications | All Things Foretravel unless you have the optional Aqua-Hot.

One very inexpensive thing to do is to make sure that all of the electrical connections on the furnace are tight. I spent quite a bit of time trying to figure out why my front furnace wouldn't light. I happened to touch one of the connections and it immediately lit. Of course, it went off just a quickly when I jumped back and dropped the screwdriver. Turned it off, tightened the connection, turned it back on and all was fine.

There is something about driving on rough roads and screws loosening.

Re: Random Questions on Heating

Reply #11 – October 17, 2021, 07:48:12 pm

Thanks for the replies, very appreciative of this! I was able to look into this today. I can confirm I had 2 furnaces, front and rear. Here is what I did, all passed-

1- checked sail switch continuity
2- checked limit switch continuity
3- confirmed 12v on on/off switch
4- checked 12v on 7A relay
5- checked continuity on 4 post relay
6- pulled board, compared it with the front, they are the same #, so I swapped them. Result is the same, rear does not ignite. This tests the igniter electrode on the board too. As I write, I supposed I can swap them again and confirm the front works still
7- checked continuity on both rear solenoid gas valves as well as one of the fronts. All were about 20.9 ohms

I do not hear the CLICK, but the fan motor does run. I guess I need to break the line replace the gas solenoid valve. Anything else to check before this? What is this? If I do need to replace the gas valve, do I have to remove the entire unit or can it be done in place?

There is a single wire switch on the backside of the gas valve

Re: Random Questions on Heating

Reply #12 – October 17, 2021, 08:30:41 pm

Do you have a cargo bay door that opens so the door lifts up in front of the heater exhaust outlet on the side of your coach? I found reference in a old thread about a "safety switch" on the bay door that is supposed to prevent the heater from running if the door is open. If the switch was faulty, it might prevent the heater from working even if the door is closed. Pretty slim possibility, but thought I'd mention it.

Front furnace

If it was me, I think I would take a chance, order a Dinosaur board, and try it before I got into replacing the gas solenoid valve. Depending on how your furnace is mounted, getting at that valve could be a pain in the butt. 7 years ago my front furnace was giving me fits. Having heard many good things about the Dinosaur line of replacement electronic boards, I decided to try one in my heater. The original problem I had with the heater was "intermittent operation". With the thermostat set to maintain a given temperature, the heater would come on one time (or several times) and work fine. The next time it came on, it might (randomly) run the fan but the burner would never light. Then the fan would continue running, blowing cold air, until I recycled the ON-OFF switch at the thermostat. One of the selling points of the Dinosaur board is it will try for a light 3 times, instead of just once like the OEM board. In case of a little air in the gas line, or very windy conditions, this would help assure that the furnace will operate when required. Another good point about the Dinosaur board: it has a built-in LED that glows "green" when power is directed to the board by the thermostat, and "Red" when the gas valve is opened. This can help verify correct wiring and operation.

The Dinosaur board was ordered from Amazon (Amazon.com: Dinosaur Electronics (UIB S) Small Universal Ignitor Board :...). It was exactly the same size and shape as the OEM board, mounted in the same place, and the original wiring connector fit perfectly. When I first tried the heater after installing the board, it would not light due to air in the gas line. I could distinctly hear the board making 3 attempts to "light the fire". Once the gas started flowing, the furnace worked perfectly, starting and stopping exactly as it should. I later bought another Dinosaur board to install in my rear furnace. Both heaters have worked perfectly ever since. Below is a link to my old furnace repair thread from 7 years ago:

Need Hydro Flame Furnace Burner

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Re: Random Questions on Heating

Reply #13 – October 17, 2021, 10:30:22 pm

Before replace valve or board check and make sure you are getting 12 volts to gas valve. If 12v and doesn't click then you know bad valve

Re: Random Questions on Heating

Reply #14 – October 18, 2021, 12:18:55 am

Sure sounds like the problem I had, first with the front furnace, and then with the rear furnace. But different years and still same exact problem.
I replaced front thermostat and the front furnace then worked fine.
Year or two later same problem with the rear furnace so I replaced that thermostat. Furnace then worked fine.
Thermostat cost? $27+ tax. (each)
I got a 10% discount because we had bought our coach there about six or seven years earlier. Nice, huh?

Re: Random Questions on Heating

Reply #15 – October 18, 2021, 11:03:44 am

google resetting dometic thermostat. might be worth a try

Re: Random Questions on Heating

Reply #16 – October 18, 2021, 11:17:13 am

If your gas stove top lights, you don't need a solenoid valve.

Pierce

Re: Random Questions on Heating

Reply #17 – October 18, 2021, 11:34:09 am

The stove works fine, DW uses it all the time.

Re: Random Questions on Heating

Reply #18 – October 18, 2021, 03:42:36 pm

Quote from: Pierce & Gaylie Stewart – October 18, 2021, 11:17:13 am

If your gas stove top lights, you don't need a solenoid valve.

The solenoid valve for the propane stove and the solenoid valve for the propane furnace are not the same thing.

In this thread, we are discussing problems with the propane furnace.

Re: Random Questions on Heating

Reply #19 – October 18, 2021, 03:55:55 pm

I am inclined to get a dinosaur board, mine looks original. Worst case it's a backup for when something goes out and if supply chains are still disrupted. $83 currently.

Regarding the solenoid valves, if I jumper one, will it click? Or do both need to be jumpered (assuming it works properly)?

Re: Random Questions on Heating

Reply #20 – October 18, 2021, 04:16:05 pm

Duh, here is what I did when the front furnace started acting weird and not staying lit. I swapped the front thermostat for the back thermostat and then the front furnace worked fine and the back furnace didn't. So simple I was surprised I didn't think of it before the DW did. (me bad)
Try it
Another thing you might try, if your furnace has a reset button on it like ours. Open the outside door on the furnace. Do you see a reset button up near the top of the unit? If so, reset it. Close the outside door and go in and try starting the furnace.

Re: Random Questions on Heating

Reply #21 – October 18, 2021, 04:18:55 pm

Quote from: Jason – October 18, 2021, 03:55:55 pm

Regarding the solenoid valves, if I jumper one, will it click? Or do both need to be jumpered (assuming it works properly)?

Pg. 25 in the manual I linked in Reply #6 (above) tells you how to test the coils on the gas valve. The two coils operate in parallel. Applying 12V power (with a jumper) to Terminal #1 should cause that solenoid to "click". Applying 12V power (with a jumper) to Terminal #4 should cause the other solenoid to click.

Re: Random Questions on Heating

Reply #22 – October 18, 2021, 05:03:34 pm

Quote from: Chuck & Jeannie – October 18, 2021, 04:18:55 pm

Pg. 25 in the manual I linked in Reply #6 (above) tells you how to test the coils on the gas valve. The two coils operate in parallel. Applying 12V power (with a jumper) to Terminal #1 should cause that solenoid to "click". Applying 12V power (with a jumper) to Terminal #4 should cause the other solenoid to click.

doh! I have been looking at this manual a lot. Specifically with the solenoids, I checked the continuity of them but I guess I missed the other section. Thank you

Re: Random Questions on Heating

Reply #23 – October 18, 2021, 07:35:41 pm

TLDR, it is working.

I jumpered both solenoids individually, both clicked. I then jumpered the lead from the control board that does both of them, this worked too. I noticed that one of the wires on gas valves was off, so my thinking is I had a wire that was not attached well(like David mentioned).

I may get one of those dinosaur boards and keep as a backup. Both of mine are original it appears and at $83, worth the cost for any supply chain interruptions occurring. Another positive is I now know much more about how these work for the next thing that may come. Thanks for the help and links to documentation/products.

Re: Random Questions on Heating

Reply #24 – November 03, 2021, 06:32:12 am

To circle back on the electric heaters, do you winterize the coach still? If a single electric heater is run and the propane heater on at its lowest as backup,, is winterizing needed still? Being in Texas it doesn't go below 32 that often and certainly not for prolonged times. I'm not against doing this but don't want to do unnecessary work.

On a similar vein, how do you use the coach when going through colder climates? Are the heater(s) enough to not freeze anything? Example, let's say it gets below freezing at Q, or you're doing a trip to Alaska, how do you prevent the coach from freezing? Obviously you cannot winterize it because you're using it. I know there are ducts to the lower bay, but is keeping the cabin area normal temperature enough to prevent freezing?

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