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Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: JB on November 06, 2021, 10:17:19 am

Title: Heat strip operation
Post by: JB on November 06, 2021, 10:17:19 am
Still a newbie trying to get up to speed with coach.
First days ever running heat.
Nacogdoches has been in upper 30's for low and mid 60's for high last couple days.

I have both zones set to heat strip on automatic for set temp of 61.

One zone kicks on more than the other and cycled on for an hour before going off for minutes before cycling back on again and is still going now 20 minutes in...that's been since 6 this morning.

I'm just trying to see if that's normal operation since I have no familiarity with RVs generally, or mine specifically.

Any input or guidance is greatly appreciated.
John

Title: Re: Heat strip operation
Post by: Chuck & Jeannie on November 06, 2021, 10:42:34 am
Need more info:  What model roof air conditioner units do you have.  What does the wall mounted thermostat(s) control pad look like - how many buttons - 4 or 5 or ?.

Title: Re: Heat strip operation
Post by: Rich Bowman on November 06, 2021, 12:35:56 pm
Turn both up to 70-75 and both should run constantly until the coach warms up to set temp.  Then they should cycle on/off as needed to maintain set temp. I don't know where your temp sensors are located for each zone.  I'm not even sure where mine are, but they work well for me.

Rich
Title: Re: Heat strip operation
Post by: Realmccoy on November 06, 2021, 10:34:34 pm
If your coach is like mine, a 98 36' U270 with original heat strips in the dometic duo therm AC units that are ducted through the roof, you have a temperature sensor in the bedroom for the rear unit below the original TV in the cabinet (passenger side) drawers. It's round, brown, and a vent about the size of a silver dollar. The temperature sensor for the front unit is part of the four button thermostat. It sits behind the driver and is affected by all the windows, an exterior wall, and windshield to front. It will always call for more heat. Mine cycles short, long and in-between.
Title: Re: Heat strip operation
Post by: JB on November 06, 2021, 11:29:12 pm
Thanks all...
I have gone through several inches of receipts and invoice to try and gather as much info as I could.
Best I can tell, 2018 two new Dometic roof AC units with heat strips were placed.
Don't know if it was then or not, but there was a new 5 button Dual Comfort thermostat/controller installed that runs the show.
At some point in 2019 there was a MoT invoice to check Zone One but it was noted as operating normally when tested.
I have now set it to 62 on furnace so I can get used to that operational sequencing and noise...
I really really appreciate y'all lending your expertise.
On a side note, I found the contact number for my coach's previous owner and we had a grand ole chat for over an hour. He lived in 'Bertha' for 16 years before trading her so I could pick up and carry on the mission...
Thanks again to all,
John
Title: Re: Heat strip operation
Post by: Barry & Cindy on November 07, 2021, 09:53:27 am
Using heat strips vs furnace or small 120v portable heaters:

Heat strips are on ceiling and with heat rising, upper air will be warmer than lower air and wear & tear is from roof air units.

Other heat sources can heat, but roof air is the only unit to cool, so it may be better to 'save' it for cooling.

Of course, there are other factors when deciding how to heat. Since we never heated with heat strips, during one of our roof air coil cleaning projects, we easily removed heat strips for better access to evaporator coil and only use two small floor heaters and furnace sometimes to heat.
Title: Re: Heat strip operation
Post by: John Duld on November 07, 2021, 12:05:13 pm
Another option,
Since your not running the compressor wear on the a/c unit is restricted to the fan, that amounts to little or nothing.
Heat does rise so heat from a space heater will end up at the ceiling anyway. If the ceiling unit is running you have the heat and circulation from that unit to provide a more even temperature in that area.
When I was plugged in and needed heat the strip heat was my first choice. Most of the time the front unit would run all night without cycling.
Comfortable when we went front in the morning. 
Title: Re: Heat strip operation
Post by: JB on November 07, 2021, 01:07:23 pm
Thanks for the input...
It helps to learn others experience.
One thing I'm going to do to address some of the thoughts expressed, I bought a 10" battery operated camping fan that I'm hanging from the driver side box where the old tv was. That will blow air from the ceiling towards the bedroom to try an equalize the ceiling/floor difference in temperatures.
Something I picked up reading some of y'all's past posts.
Thanks again...
John
Title: Re: Heat strip operation
Post by: "Irish" on November 07, 2021, 11:06:11 pm
Heat strips are fine for moderately cold weather but they do not heat the bays especially the wet bay, you must use the furnace mode which is the forced air furnace to keep the tanks and pipes from freezing.
Good luck: we love out '99 U270
David
Title: Re: Heat strip operation
Post by: Rich Bowman on November 08, 2021, 09:07:44 am
Electric heat strips and propane can give you a lot of redundancy.  When it gets down into the single digits, you can use a lot of propane.  You may have to refill every 3-4 days.

I can operate down to about 0 degrees F on just electric.  I have a Lasco 200W forced air heater in each wet bay.  They are about as worm as a big light bulb but have a fan to move the air around.  And I add a sheet of 1/2" foam insulation board inside the door to help keep the heat in the compartment.  I velcro them to the floor and can use them on the inverter while driving.  At 0 degrees F, it takes an additional one or two small electric heaters inside also.  You do have to manage which 50A leg and individual 20A circuit you are using so you don't overload a breaker.

Things stay toasty and I don't have to worry about moving to fill propane when it is cold and potentially snowy.

Rich
Title: Re: Heat strip operation
Post by: Barry & Cindy on November 08, 2021, 10:56:09 am
Thanks Rich & Peggy for reminding everyone about 200watt Lasco Personal Heaters that have keep us safe during freezing temps.

We have 4 of them, all plugged into one power strip and have a couple of spares heaters. We use a large piece of Reflectix just inside bay door that has all 4 sides folded in to help contain heat. Wireless thermometers keep us informed of temps on the other side of the Refectix.

Just can't count on furnace to warm every corner of water bay plumbing. Even our big bay may have liquids we don't to freeze.

We manually turn Lasco heaters on and don't rely on auto temp switches for these heaters.

For coach interior we also use a couple of 700/1500 heaters.

BTW all electric heaters are plugged into our several outlets that are not on inverter that we have spread out in coach, to protect our batteries from draining if we lose electric power. Each outlet not on inverter is identified with a different color face plate.

Refectix on inside of windshield helped a lot.

Of course, now that we are staying out of freezing temps, it makes all our cold weather gear redundant.

Barry
Title: Re: Heat strip operation
Post by: JB on November 08, 2021, 11:34:11 am
Barry...

Thanks for note.
If I may ask, is there an experience you had that soured you on the thermostatic controlled thermocubes I've read about?
I've bought a couple that come on at 35 and off at 45 that I was going to plug the 3 Lasko 200 watt personal heaters I've bought into...

Thanks,

John
Title: Re: Heat strip operation
Post by: Barry & Cindy on November 08, 2021, 10:58:13 pm
Good question John...

I do like automatic controls, especially if not living in coach. We have not lived in cold freezing temps for a while. Probably the main issue is where the cube is located, and does it really know if there is a very cold spot away from the cube's outlet or extension cable end?

With freezing a single pipe being such a big deal, maybe I feel more in control if I turn heaters on and leave them on even if temps rise above set point at the place the thermostat is located. Maybe living full time for 20 years make me want to manually control heaters as we are always home.

When we started years ago I once used a light bulb to heat bay and that was quite dangerous even with a cage around the bare bulb. When we found Lasko 200 watt, felt they could be on and never cause a fire from too much heat in one place. I really wanted to reinforce your posting promoting Lasko and just got carried away with the details of our story. Our Lasko's are all in place but have not been turned on in many years.

To make it easier to turn on, I ran a power cable up into coach interior and plugged it in. I could have used a remote 120v switch, like the one we use for our built-in vacuum.

Give the Cube a chance and maybe they would be a good backup to turn heaters on if you did not do it manually.

Being in warmer temps year around may be in your future and then no pipes will freeze.

Enjoy,

Barry
Title: Re: Heat strip operation
Post by: WagonWheels on November 09, 2021, 05:17:02 pm
A quick look thru my Duo-Therm manual indicates the unit is both an A/C and a heat pump.  Heat pump means the unit runs in reverse trying to cool the outside and dumping the warm air inside.  Some units come with a heat strip.  See the picture below about the dip switches.  On this unit the dip switches are under the shroud.  I personally don't like to operate the heat pump since it's noisy and puts strain on the compressor, i.e. saving the compressor for A/C needs in the summer.  We use a portable electric heater along with Aqua Hot, electric setting.  Only need the AQ diesel setting in really cold weather such as we experienced in El Paso last Feb.  If you have a propane furnace then there are different issues.  A lot of boondockers swear by the catalytic propane heaters.  Very efficient use of propane and use no 12VDC.  One drawback is excessive water vapor which requires keeping a window slightly open.