Thermostat Question

[oilbegone]

Hello,
Just hooked up a Solo 30 with oil backup, 620 gal. storage tank and a Honeywell Vison Pro 8000 thermostat that has two stages. As far as I can tell the differential between the wood and oil is preset in the thermostat and can not be adjusted. I acts like it is just over one degree of difference. When the heat is being maintained during the set schedule at say 67 degrees the oil does not come on. In the morning when the heat kicks on from the night time set back the oil comes on as backup and the same thing at night when the day time set back ends.
My question is can I cut a second thermostat into the W2 (blue wire) and set that thermostat at what I want the differential to be. That way when the Vision Pro calls for the second stage the oil burner will only come on if the house temperature is below the second thermostat setting.
If this works it may be good information for a lot of people that have a similar set up to mine.

Thanks
Clint

 

[Nofossil]

I don't know about yours. I use the Carrier Debonair 33cs071 commercial thermostats - these have stage 1 and stage 2 outputs, programmable deadband, and a separate programmable 'unoccupied' temperature. Stage 1 is setpoint minus deadband, and stage 2 is two degrees below that.

There's a pair of contacts that allow you to externally control whether the thermostat uses the 'occupied' or 'unoccupied' settings.

I control the thermostats based on where my heat is coming from.

If I'm heating with the wood boiler, my thermostats are set to 'occupied' and I use the stage 1 contacts to control the zone valves. This results in a living space temp of 71-72 degrees.

If I'm heating from storage, I'm still 'occupied' but I use the stage 2 contacts, resulting in living space temps of 69-70 degrees.

If heating from oil, the thermostats are set to 'unoccupied' and the temp is 60 degrees. Only happens if we're away.

 

[oilbegone]

Thanks for the info nofossil, the Carrier model you mentioned si soooooooooo much more flexible. Anybody want a Vision Pro?

 

[BrownianHeatingTech]

Just hooked up a Solo 30 with oil backup, 620 gal. storage tank and a Honeywell Vison Pro 8000 thermostat that has two stages. As far as I can tell the differential between the wood and oil is preset in the thermostat and can not be adjusted. I acts like it is just over one degree of difference. When the heat is being maintained during the set schedule at say 67 degrees the oil does not come on. In the morning when the heat kicks on from the night time set back the oil comes on as backup and the same thing at night when the day time set back ends.
My question is can I cut a second thermostat into the W2 (blue wire) and set that thermostat at what I want the differential to be. That way when the Vision Pro calls for the second stage the oil burner will only come on if the house temperature is below the second thermostat setting.
If this works it may be good information for a lot of people that have a similar set up to mine.

What do you have parameters 0240 and 0250 set to?

Joe

 

[oilbegone]

I am going to leave it like it is set up for now monitor the situation and change thermostats if the oil burner comes on too much. The oil only comes on for a few minutes a day and gives the oil burner a little exercise brings it up to temp etc. If anybody has any thoughts on the merits of leaving the oil off all the time or running it 3 or 4 minutes a day I am all ears.
I still can't believe the control you have with a wood boiler, storage and an air handler. I used to be pretty proud of heating my house with the old wood stove but now realize how primitive that was. Burn On!

Joe at first I did not notice your post they are both on 5 - standard fossil fuel forced air systems.

 

[BrownianHeatingTech]

Joe at first I did not notice your post they are both on 5 - standard fossil fuel forced air systems.

Lower CPH = larger differential.

Joe

 

[oilbegone]

Thanks Joe

What would you recommend as a starting point for the 0240 and 0250 settings.

 

[BrownianHeatingTech]

What would you recommend as a starting point for the 0240 and 0250 settings.

Without knowing your system, I wouldn't.

Best bet is to just experiment, anyway. Try dropping them both down to 1CPH tonight, and see what happens in the morning.

If that solves it, then try moving each one individually. It will always be a balancing act, based upon your personal comfort. I've run an oil furnace at 1CPH for years, because I didn't mind the temperature swings, but I did mind buying oil.

Joe

 

[oilbegone]

Ok I will try experimenting over the next few days and report back the results.