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Old 09-23-2012, 08:13 PM   #1
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Dometic Briskair thermostat not working on heat

I got the heater strip option for my Dometic Briskair and the thermostat does not seem to be in the loop. It is either on or off and it does not cycle with temperature which is not acceptable whether by accident or design. It got cold last night when we were camping and I turned on the heater strip and I woke up in the night sweating because it was 80 degrees in the trailer. I turned it off and by morning the wife and I were cold again.

Is this normal or is something FUBAR?

Perry
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Old 09-23-2012, 08:35 PM   #2
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Which t/stat do you have and what is the model number of the BriskAir ?

It could be some simple settings, but they depend on what you have.

Get back with the info and an answer will be forth-coming.....
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Old 09-24-2012, 07:56 AM   #3
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See if this helps.



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Old 09-24-2012, 07:49 PM   #4
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Well according to outdoors mart there is no thermostat on heat mode. This really sucks in my opinion. The 1600W or so is plenty of heat to heat a trailer in the southeast it the temps are above 30F. The whole reason I bought the heater kit was to use it as the primary source of heat. The furnance is for emergencies. They sorta got you. If you modify it the warrantee is void. If you don't then it is useless.

Perry
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Old 09-24-2012, 08:10 PM   #5
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Perry,

Unfortunately, lots of folks think that a heat strip can be used instead of a furnace (or heat pump for that matter) but they can not. About all a heat strip will do is take the chill from the air in the coach, but will not really create any heat. IIRC, most heat strips run about 500 watts....not much in the BTU department there. I had 2 Dometic units in my first motor home that had heat strips and they were all but useless unless getting rid of the chill. The furnace did the real work of heating the bus.

Still, a thermostat should read 'heat strip' so you can still operate it! Most A/C units have 'dip switches' located on the relay boards that essentially tell the thermostat what functions are in the unit and how they operate.

What does your thermostat look like?
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Old 09-25-2012, 07:21 AM   #6
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What does it look like? Well it is made into the unit. It looks like most self contained thermostats. A knob, some wires and a sensor tube coming out. The heater strip puts out plenty of heat for mild temperatures. It was probably 45F this weekend and it got the trailer up to about 80F before I turned it off. I lived in a 27 ft 5th wheel trailer in college and all I had was the heater strip in the Coleman AC unit to keep me warm in Gainsville, FL. It worked fine. I can put an Amp probe on the unit and determine exactly what the heater wattage is. The problem is with space heaters is that the secondary AC power does not have enough wattage to run a heater. Most of the Amperage capacity is going to the AC and the Microwave oven. Having a heater in the AC unit simplifies life when the unit is at home hooked to shore power. I am going to fix the above problem before long. There needs to be a 20A circuit for heaters in the rear bedroom.

Back to the AC unit. It would not be hard to rig a thermostat to the heater. I could rig a solid state relay to turn the heater on and off and control it with a simple bimetal thermostat. If I can get 12V over to the unit to power the relay electronics, it would make life easier. I might also be able to find a mechanical thermostat that was big enough to control the heater. I have an old coleman with the heater strip. Maybe it has the bi mode thermostat. I do remember having to replace that thermostat periodically when the points would stick together inside it.

Perry
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Old 09-25-2012, 07:28 AM   #7
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Hi Perry,

So, you have the in-line rotary controls on the unit. I thought that you might have had a separate, digital remote t/stat that does have the heat strip programmed into it. My error!

Unfortunately, rotary analog controls don't. It's just hit and miss, just like setting the temps when you use the A/C to cool the trailer.
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Old 09-25-2012, 08:02 AM   #8
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You may be able to modify it to control the heat strip. We did. Call Dometic with your model # and serial # to see if they have a kit. It did require running some wire which was a challenge. The t'stat also controls the furnace now. One drawback is that now we can't run the furnace and heat strip at the same time.
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Old 09-25-2012, 09:00 AM   #9
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Lewster

Does the rotary thermostat have a double pole contact? It it has the two contacts then I can just run my heater off that.

Perry
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Old 09-25-2012, 09:29 AM   #10
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Hi Perry,

I have a Carrier with a heat pump that has the control on the lower unit. Different AC, similar control. I have found that I have to turn the knob much further clockwise to get the heat to the same temp as the cooling. You may have the opposite problem. The knob type "thermostats" are pretty crude mechanical devices. You may have luck if you turn the knob way down further than you would think given how cold it would get in cooling mode.

Personally, I have pencil marks on my lower unit. One range for cooling and one for heating. Crude, but it works.

Best of luck.
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Old 10-12-2012, 08:52 PM   #11
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Ok here is the $20 fix. You can buy a thermostat for baseboard strip heaters that will control the heater strip using a bimetal thermostat and heavy duty contacts. All you have to do is wire the thermostat in series with the heater strip. I will probably do this, this weekend and I will report back. Most of these things are 4 wire with two separate contacts inside them. You will only need one of the two sets of contacts. You would use 2 if you are using 220V which does not apply here. I will need to figure out a good way to mount the thermostat. I am sure I can find room for it in the air distribution box but I don't want to do that till I get finished BETA testing (AKA smoke test).

Perry
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Old 10-17-2012, 08:41 AM   #12
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Contrary to popular belief the internal heater strip does produce a significant amount of heat. It is 1500W which is about 5000 BTU's or about what your typical space heater puts out on high. It is clean, it is free if you are already paying for electricity. The fan stays on all the time so you are not awaken by the furnance turning on and off. It is safer because you don't have the potential for fire or fumes. Yes I know, when the temps get below the 30's you are going to need more heat. Until then which is 99% of the time in the southeast, you can use the heater strips. In the southeast the furnance is like lighting a BBQ grill with a rocket engine. It is way overkill for many of us but it is a nice backup.

I have still not installed the thermostat but I hope to this week.

Perry
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Old 10-17-2012, 09:05 AM   #13
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I agree with Perry. My Carrier is a heat pump unit and it heats the trailer really well down into the 30s, then it switches to the heat strip. The amount of heat the strip puts out is still well worthwhile.
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Old 10-17-2012, 09:15 AM   #14
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I pulled the wattage numbers right off the heater strip so they were not pulled from my back side.

Perry
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