Air Handler Fan Control for Hot Water to Hot Air - Suggestions Needed!

[JTWALL]

Okay...let's see if I can do this in a thousand words or less :-(

I have been assisting someone (via the internet) with questions related to an Eko Model 40 installation.
He will have 1000 gallons of storage.
His home has a propane-fired hot air furnace.
He has to install a water to air coil in his existing hot-air plenum.
Does anyone have experience or knowledge on how to control the furnace blower so that it can work with either the regular propane-fired furnace or the Eko?
With the Eko's storage tanks up-to-temperature, he needs to turn on the blower motor only (not the propane burner).
He would like it configured so that if the Eko can't supply hot water (he is away or the boiler has run out of firewood), the propane burner would take over automatically.

Any thoughts?

Thanks!
JT

 

[goosegunner]

Here is the wiring diagram my HVAC guy came up with to run my system.

I have zone dampers in my forced air system so it may be more difficult but this is what it does.

Call for heat kicks on pump and fan
Time delay for 3 minutes
If temp from aqua-stat at exchanger is not 130 after 3 minutes it stops signal to pump and lp furnace burner kicks on and runs as normal.

I work 24 hour shifts so if my wife doesn't get to the boiler the switch in heat source is seamless. I have had times when I see the exhaust from the lp furnace and realize whoops, storage needs to be recharged.

gg

 

[JTWALL]

Here is the wiring diagram my HVAC guy came up with to run my system.

I have zone dampers in my forced air system so it may be more difficult but this is what it does.

Call for heat kicks on pump and fan
Time delay for 3 minutes
If temp from aqua-stat at exchanger is not 130 after 3 minutes it stops signal to pump and lp furnace burner kicks on and runs as normal.

I work 24 hour shifts so if my wife doesn't get to the boiler the switch in heat source is seamless. I have had times when I see the exhaust from the lp furnace and realize whoops, storage needs to be recharged.

gg

Excellent! Thanks for taking the time to share this information! I have forwarded this link to the person who needs it. Regards.

 

[heaterman]

Same thing without the time delay.

The aquastat pictured can be a strap on type mounted near the plenum if you are using a constant circ set up as is common amongst the OWB installers. Or, you can use a well type aquastat in your thermal storage tank that looks at the temp there.
Typically the coil in the penum will heat up so quickly that we don't bother with the time delay unless the storage is a great distance away from the coil.

We'll set the aquastat typically around 130-140 to provide good usable and comfortable discharge air temps. Below that the SPDT aquastat will make to the furnace instead of just the blower via the B terminal on the switch.

 

[JTWALL]

Same thing without the time delay.

The aquastat pictured can be a strap on type mounted near the plenum if you are using a constant circ set up as is common amongst the OWB installers. Or, you can use a well type aquastat in your thermal storage tank that looks at the temp there.
Typically the coil in the penum will heat up so quickly that we don't bother with the time delay unless the storage is a great distance away from the coil.

We'll set the aquastat typically around 130-140 to provide good usable and comfortable discharge air temps. Below that the SPDT aquastat will make to the furnace instead of just the blower via the B terminal on the switch.

Thanks! I have forwarded the information.
Regards...