changing Old heat only thermostat to programable

[NW Lady]

I have an 1999 Ford coachmen class B.

I would like to change out the 22 yr old thermostat for a programmable one. It is for Heat only. AC is on different system.

Is this possible? Does anybody know a manufacture/model that would work?

Seems like Honeywells are all 24V. I am assuming the one I have is 12 v.

Thank you

[avanti]

Most any inexpensive thermostat that has a battery in it will work. The electronics of the stat are powered by the battery, and the connection to the heater is just a relay, so it doesn't care whether it is 12V or 24V. Check out Home Depot.

[NW Lady]

thank you!

[Roadtrek Adventuous RS1]

Hmm, I guess ?? But, why would you need to do that if your old thermostat is working???

Look, it a 1999 RV..... what could be so important to change to a programmable unit like this....

I could see that if you're installing a Nest Thermostat in your house , but, the RV???

I would recommend that you save the money and skip it....

As long as you have a thermostat that works and holds the temperature you set it at ...... keep using it.....

When you don't need heat just turn off or lower the set temperature.... simple is sometimes better.

[Bertiboo]

Originally Posted by NW Lady

I have an 1999 Ford coachmen class B.

I would like to change out the 22 yr old thermostat for a programmable one. It is for Heat only. AC is on different system.

Is this possible? Does anybody know a manufacture/model that would work?

Seems like Honeywells are all 24V. I am assuming the one I have is 12 v.

Thank you

It is likely that your existing thermostat is a millivolt unit. In an mv system, the voltage, about 750 mv or 0.75V is produced by a standing pilot light heating up a thermopile. Since there are no electronic thermostats that can run on these voltages, you would need a battery powered unit.

[avanti]

Originally Posted by Bertiboo

It is likely that your existing thermostat is a millivolt unit. In an mv system, the voltage, about 750 mv or 0.75V is produced by a standing pilot light heating up a thermopile. Since there are no electronic thermostats that can run on these voltages, you would need a battery powered unit.

I think she is talking about her furnace's air temperature thermostat, not the internal ignition sensor, so that shouldn't be an issue.

However, she will still need a battery-powered unit, due to the 12V/24V issue.

[Bertiboo]

Originally Posted by avanti

I think she is talking about her furnace's air temperature thermostat, not the internal ignition sensor, so that shouldn't be an issue.

However, she will still need a battery-powered unit, due to the 12V/24V issue.

Yes, in a 2 wire millivolt system, the wires run up the wall to the thermostat as well as powering the internal gas valve. Easy enough to tell by measuring voltage at thermostat.

[avanti]

Originally Posted by Bertiboo

Yes, in a 2 wire millivolt system, the wires run up the wall to the thermostat as well as powering the internal gas valve. Easy enough to tell by measuring voltage at thermostat.

Oh, I see. The thermopile output is sent up to the thermostat. I guess that would be used in a heater with a non-powered ignition system. Kind of like old-school water heaters.

This is new to me. Thanks. Were these really used in RV systems?

As you say, either way, a battery-powered stat should work fine.

[NW Lady]

Thank you for the info.. I thermostat I am looking at does have batteries Honeywell RTH2300B. The idea of don't fix what isn't broken is valid.... the little "on/off" switch is getting almost impossible to move. ... it has such a wide temp swing. This unit is about about $7 more expensive than the type that is currently installed ..an old atwood.

I am always so amazed at the knowledge and experience of the folks on this site and their willingness to share and help. Many Thanks.

[avanti]

The reason we replaced the ancient Atwood stat on our previous rig was that it made an obnoxious "clunk" sound every time it switched the heat on or off. Actually would wake us up at night.
For the price of a modern, silent thermostat, it was a no-brainer.

That Honeywell should work fine.

[NW Lady]

Yes!! Things that go "clunk" in the middle of the night are annoying!! Mine does the same thing!

[ChicagoTom]

Ex-HVAC guy many many years ago, so IMO replace with like for like. Most RVers don't understand that in a Class B you don't want it too accurate, because the space is so small. For example, the existing Suburban T-Stat may bring it a couple of degrees higher and shut off, the programmable and more accurate digital will cause the unit to come on and off more frequently. Not a problem if you're plugged in, but boondocking it'll drain the battery quicker. The comfort difference is not noticeable, unless you sleep in your birthday suit with no covers on...Bottom line, KISS My Suburban's little on/off tab broke, so I replaced it. I now know to grip it better when turning it on or off. Again, all JMO

[Roadtrek Adventuous RS1]

Originally Posted by ChicagoTom

Ex-HVAC guy many many years ago, so IMO replace with like for like. Most RVers don't understand that in a Class B you don't want it too accurate, because the space is so small. For example, the existing Suburban T-Stat may bring it a couple of degrees higher and shut off, the programmable and more accurate digital will cause the unit to come on and off more frequently. Not a problem if you're plugged in, but boondocking it'll drain the battery quicker. The comfort difference is not noticeable, unless you sleep in your birthday suit with no covers on...Bottom line, KISS My Suburban's little on/off tab broke, so I replaced it. I now know to grip it better when turning it on or off. Again, all JMO

It's not like the system in your primary residence and always connected to the Internet......I'm all about high tech stuff, but, it's just a vehicle and very small....

Sometimes it's better to stick with stuff that just works....I think a lot of people sometimes over think these things....
You're basically sleeping overnight and want the system to keep you warm....I manually turn off the heat when I'm not in the RV... When I need heat, I come back and turn it on.... easy.....It only takes a few minutes to warm up the vehicle.

If your existing thermostat is broken, yes, replace it with a similar unit.....

Great advice.

[avanti]

Originally Posted by Roadtrek Adventuous RS1

a lot of people sometimes over think these things....

You can say that again!

The Honeywell will work just fine.

[ChicagoTom]

Originally Posted by Roadtrek Adventuous RS1

It's not like the system in your primary residence and always connected to the Internet......I'm all about high tech stuff, but, it's just a vehicle and very small....

Sometimes it's better to stick with stuff that just works....I think a lot of people sometimes over think these things....
You're basically sleeping overnight and want the system to keep you warm....I manually turn off the heat when I'm not in the RV... When I need heat, I come back and turn it on.... easy.....It only takes a few minutes to warm up the vehicle.

If your existing thermostat is broken, yes, replace it with a similar unit.....

Great advice.

Well said. I'll never understand why some want to make the Calss B a high tech PIA. I lived full time, all stock except a 100 Watt that I slap up and down above the windshield. KISS

[NW Lady]

Thank you, chicago Tom... good points! It is getting really hard to use so I will just get the similar/same thermostat. Last thing I want is to be wasting my electricity. Maybe a newer one won't make such a "clunk" when it starts up.

Many thanks!