outside temp cut off for stove

[rmm69]

I have a harman xxv . I use it when the outside temp dips below 30deg to prevent propane furnace from coming on. I would like for the xxv to cycle off when the outside temp reaches 35deg. then my heat pump will take over. Planning on using an a-19 type t-stat with outside sensing bulb. Not sure on how to connect with stove . Have any of you done this and willing to share ?

 

[jtakeman]

Stat goes in the room probe circuit. Remove one wire from the probe and install the stat in series with it.

Explain the a-19 type t-stat with outside sensing bulb? Never heard ov it, Might be handy. I think it needs to be a millivolt stat, by the way(Harman peeps correct me if I'm wrong!).

 

[Don2222]

Hello

The A19 series thermostat provides remote bulb or coiled
bulb sensing for hazardous environments. See pic below.

I think that you may be better off with a Digital Millivolt T-Stat made for pellet stoves that have a swing setting such as a Lux 9000TS available at Lowes

See
http://www.lowes.com/pd_225410-3742...l__0__s?Ntt=thermostat+lux+ts9000&facetInfo;=

Slso for more pellet stove T-Stat info see
https://www.hearth.com/econtent/index.php/forums/viewthread/80457/

 

[rmm69]

Don thanks. But will it work for what i want to do by shutting down at a outside temp set point?

 

[Don2222]

Don thanks. But will it work for what i want to do by shutting down at a outside temp set point?

Ok, I see what you need.
If you put the A-19 T-Stat in series with the Lux 9000TS and set the A-19 to 35 Degrees you will be all set.

Then you can set the Lux for the desired room temperature inside your house and with the A-19 sensor outside the house, the stove will shut down when the outside temp is above 35 degrees!

 

[tjnamtiw]

You are assuming that your heat pumps are more efficient than the pellet stove once the outside air gets to 35? I have heat pumps too and had similar thoughts but could never get good, firm numbers of COP at various temps. Very interesting. I assume your outside sensor is a NO contact above your setpoint.

 

[jtakeman]

What you don't want to do is cut power to the stove. You might need to use the A19 to control a relay. Have the relay in the stat circuit to just open it.

If you plug the stove into the A19 and cut power to it, There is a good chance you'll get smoke in the house. Also many stoves will default to a low heat setting if you kill power. So when you try restarting it, The stove will probably be so low it will barely warm the house.

Keep us posted!

 

[tjnamtiw]

Yea, j-t, I would put it in series with the thermostat and not the power. You would really need a SPDT relay so that it cuts out the pellet stove thermostat and cuts in the heat pump thermostat. I was thinking of just using an el-cheapo thermostat outside in an enclosure but it would have to control a SPDT relay to do the job.

 

[rmm69]

Thanks for everyones input. I know not to have stat kill power to stove because it needs to cycle off. I am planning to put in series with stove stat. Once the outside air reaches my setpoint of approx 35deg. the circuit will open and cycle off stove. The heat pump will kick in as soon as the house cools a few degrees and the house t-stat calls for heat.

 

[tjnamtiw]

Since your installation is similar to mine AND you are thinking about the efficiency of each unit and which saves the most money, you might want to look at this cost comparison page that is in my opinion the best one out there because it takes into account the type of duct work you have with your heat pump. You have a choice of how well it is sealed as well as two R values of insulation. It, in itself, is a real eye opener. Try it out. While the efficiency of a good heat pump is about 300% (3 COP) at fairly warm temps, it drops dramatically toward 100% as the temp approaches freezing. Like I said earlier, I can't get specific numbers on my units. Maybe you have better luck. In any case, for me with electric at about $0.10 KWH in the winter, it's a no brainer to use pellets until the COP gets up to 3 and then it's a wash. My ducting is in the crawl space with R4 insulation and, I assume, good redneck sealing........

http://www.buildinggreen.com/calc/fuel_cost.cfm

 

[George]

Hello, i have just joined and have been following your thread. If the link below worked it is for a preset constuction thermostat thats $14 you could put outside in series with another thermostat in the house. The stove would operate normally and only below 41* outside temperatures. Hope this helps.

http://www.prothermostats.com/product.php?p=jackson-systems_ts-41&product=110262&category=427

 

[tjnamtiw]

Hello, i have just joined and have been following your thread. If the link below worked it is for a preset constuction thermostat thats $14 you could put outside in series with another thermostat in the house. The stove would operate normally and only below 41* outside temperatures. Hope this helps.

http://www.prothermostats.com/product.php?p=jackson-systems_ts-41&product=110262&category=427

That's a slick little unit. Too bad it's back ordered until Feb! Simple and cheap.......... No, I won't go there!

 

[George]

That was the web site I ordered mine through, it has the information. They are on e-bay for a couple bucks more and a lot of heating supply web sites and local suppliers have them as well.

 

[rmm69]

Well I can inform you all that my johnson controls A-19 install is up and running. Last night temp was 28 and when it warmed up to 38 this morning the stove shut down. Thanks again for yalls input. By the way I bought 2 tons of power pellets at $189 a ton. cheapest I can find in stock here in MD.