Adding outdoor boiler to heating system

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Old 09-15-11, 06:36 PM
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Arrow Adding outdoor boiler to heating system

I just had a geothermal system installed in my house with a gas furnace backup. I have an outdoor wood furnace that use to be my primary heat, but I'm getting older and don't want to cut and load so much wood anymore. However, I would like to take advantage of the outdoor wood furnace for the 3-4 weeks a year when we get sub zero weather.

I have plumbed the heat exchanger for the wood furnace into the air handler and have a Honeywell v8044 3-way zone valve to control letting the water through the exchanger when there is a call for heat or otherwise just bypass it back to the wood furnace.

My new system has a Honeywell HZ432 zone panel set up with 2 heat stages Y1 & Y2 going to the geo heat pump and back-up/emergency (W1/E) going to the furnace.

What I would like to do is use a relay to switch Y1 from the heat pump to the 8044 zone valve when the wood furnace is on. I would use a thermal switch like they use on wood stove blowers to activate the relay. So when the water coming from the wood furnace is say <140F (ie. wood furnace off) the system will run as normal, but when the water from the wood furnace is >140F, the relay would switch Y1 to the V8044 and the first stage of heat would just open the zone valve to the wood furnace heat exchanger.

My questions are:

1) Would any damage happen to the geo heat pump if it got a call for 2nd stage (Y2) without a call for Y1 first/also?
2) Can the Y1 output of the HZ432 drive the V8044 zone valve?
3) When Y1 is driving the zone valve, will the HZ432 still turn on the furnace blower? It does have the G to G line connected to the furnace.

Any other advice, or if I've missed something would also be welcome.

Thank you for your time..
 
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Old 09-16-11, 06:58 AM
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Why not just let the Geo do the job for you? Save you going out tending the fire.

I am guessing the HP is two stage? Can you get the model # on tihs for us please? If we do rewire it, you going to lose one of the stage on the Geo.
 
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Old 09-16-11, 07:47 AM
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Originally Posted by Jay11J View Post
Why not just let the Geo do the job for you? Save you going out tending the fire.
That is the plan. I do still have the outdoor wood furnace and will have a couple of cords of wood each year just from blow downs and deads on my property, so why not take advantage of it. For cost reasons, the Geo was sized for like 90% of our worst case heat load, and would rely on the backup to make up the difference for those couple of weeks a year exceptions. Also, since I'm in a rural area, power losses can be quite common, and if extended periods, I can still heat the house with the wood furnace and a small generator. Tending it is just once a day.

I am guessing the HP is two stage? Can you get the model # on tihs for us please? If we do rewire it, you going to lose one of the stage on the Geo.
Yes it is a 2 stage. GeoComfort - GTC060B11CD

I'm not too concerned with loosing a stage, just want to make sure I'm not damaging the system by doing such. With the design I have in mind (explained in original post). When the wood furnace is active, the geo should theoretically never kick in. The wood furnace has handled all the heat requirements for the last 14 years. If the temperature of the wood furnace water drops, the relay should pull it out of the configuration. Of course there is always exceptions to never. I guess if the wood furnace is not stoked properly and the water temperature starts to drop, there is the chance that there will be a call for heat as the wood furnace temperature is drops below 180F, but before it hits the thermal switch/relay cut-out of 140F and may cause another stage to kick in.

Thanks again
 
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Old 09-16-11, 09:51 AM
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this is my thinking and I want hvactecfw to see if he agrees or has another ideal.

What is used now to run the fan on the system when you heated the house.

A relay may be needed here.. I some how tie into the relay you have now for the fan. Then this relay now can kick in the HP and we won't lose your two stages from that.
 
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Old 09-16-11, 07:29 PM
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Originally Posted by Jay11J View Post
this is my thinking and I want hvactecfw to see if he agrees or has another ideal.

What is used now to run the fan on the system when you heated the house.

A relay may be needed here.. I some how tie into the relay you have now for the fan. Then this relay now can kick in the HP and we won't lose your two stages from that.
After drawing out the wiring diagram, I think your right that I need to relay the blower on as well. Don't quite follow how to open the zone valve for the water though without stealing a stage of heat.

Anyway, here is the current wiring.


And here is what I'm proposing using a DPDT relay to switch Y1 to the zone valve and energize the blower.


See any issues with this? Other than loosing a stage of the heat pump.
 
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Old 09-17-11, 06:43 AM
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This should work. However the stats should already be calling for fan during stage 1 and 2 of heat if they are setup for HP operation.
 
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Old 09-17-11, 11:36 AM
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Originally Posted by hvactechfw View Post
This should work. However the stats should already be calling for fan during stage 1 and 2 of heat if they are setup for HP operation.
Yes, they are set up for HP, and that is what I was thinking, but when I drew the diagram, I couldn't comprehend how the fan would be activated when wood furnace was on and stage 1 call would just open the zone valve (not tied to Y1 on furnace or HP).

But perhaps a more basic question you could answer for me, is how do the thermostats (I have 3 zones), which have fan on or auto states, logically activate the fan since there is no connection G-G from the HZ432 to the furnace. Or after looking again, I think I might have answered my own question. The humidifier GT & GF are pass through and allows the humidifier to turn on the blower if there is a call for humidity and the blower is not already active?

If this is the case, I should be able to just use a SPDT relay for just the stage 1 heat and not put the fan through the relay.

BTW, thanks for your and Jay's help on this, I really appreciate it.
 
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Old 09-17-11, 11:40 AM
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yes, you are correct about the humidifier wiring. You are also correct about the SPDT relay
 
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Old 09-17-11, 05:30 PM
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Sorry for not getting back sooner. But yeah no reason why that can't work.. You were on the right track..

If I were you, print this drawing out, and put it near the relay/control. So that way if you had service and you were not home or sell the house. The tech will know what's going on.
 
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Old 09-17-11, 06:03 PM
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Originally Posted by Jay11J View Post
If I were you, print this drawing out, and put it near the relay/control. So that way if you had service and you were not home or sell the house. The tech will know what's going on.

Excellent idea, I will do that. All clear in my head now, but I can see pulling my hair out ina few years trying to figure out what the heck I did. Also an excellent idea if the house is sold. We were fortunate enough that when we bought the house, the previous owner had a stack of manuals for everything in the house that they left in one of the kitchen drawers. They can be a real life saver when trying to order parts.
 
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Old 09-17-11, 06:14 PM
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Originally Posted by gary425 View Post
We were fortunate enough that when we bought the house, the previous owner had a stack of manuals for everything in the house that they left in one of the kitchen drawers. They can be a real life saver when trying to order parts.
That's great! I work at Home Depot, and I can't even count how many customer comes in the store asking for parts and they have no clue what they got in their home since they didn't keep the manual/books or past owner not leaveing it behind.

It hard for me to tell the customer I am not able to help them since there no info for me to go off of. Some items I can tell what they need. but that is a very low %.
 
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