Improving heating and circulation along with a heat pump

[browneyesvictim]

My house is not laid out the most optimum for heating the whole house with the wood stove. Take a look at the house layout, you will see the wood stove is on one end of the (single story) house, and that room is relatively separated from the rest of the house. When I bought the house 4 years ago, I upgraded the furnace to a very efficient Mitsubishi minisplit inverter heat pump and newer air handler(no strip heat) that performs exceptionally well, but I want to utilize more wood stove heat to the back of the house. I am not using any of the “ductless” features of the heat pump, but rather using the existing ducting that is plumbed. The Family room the wood stove is in gets plenty (too) warm and the back bedrooms stay cooler.


This 1477 sq. ft. house is moderately well insulated and sealed. When the new HVAC system was installed, I had all the duct sealing, cleaning and testing done by an independent energy efficiency company that was required to certify the install of the heat pump for the tax credits. This Lopi Answer I installed in November is a fantastic space heater for the family room, and the heat pump does a good job maintaining a temperature of the whole house wherever I set it at but looking for ways to improve the wood heat circulation and save even more by cutting back on the heat pump.


I have tried to turn off the heat pump completely and just circulate the air with the air handler fan, but the back rooms just get colder. There are 2 air intake vents in the ceiling as marked on the layout sketch. One of them is about 15 feet from the wood stove, and the other is in the far back bedroom hallway. There are 3 ceiling fans installed: Family room, Living room, and Master Bedroom

• I’m considering blocking off the back intake vent so the intake vent near the wood stove is drawing more warm air in. (There is no diverter control in the attic) Good ideal or not?
  
  
• Those augmenting an existing heating system with a wood stove, how do you set your furnace/heat pump? Do you turn it off, circulate, or just set it at desired temperature?

My system is working well as it is, and perhaps I am splitting hairs, but I am looking for suggestions and ideas for improvement to lower my power bill. November and December bill is up 100 bucks even with the new wood stove although there was a recent rate hike. I’m going to look closer at kilowatt hours and do some log trending with inside and outside temperatures.

 

[semipro]

Bump.
I missed this one. Maybe others did too.

 

[browneyesvictim]

wow... no love...

 

[Slacker]

If you have your heat pump set to off and just have the fan in the air handler running you should be ok. But do not run the heat pump in heat with any of the returns blocked.

 

[semipro]

First thought: do you have an outside air supply system installed on your wood stove? If not, makeup air being pulled in from outdoors throughout the house may be making those rooms cold.
There are many posts in the Hearth Room about "moving the heat around". Read those.
The collective wisdom there will tell you to move cold air from colder zones to the wood stove area -- don't try to move the warm air. Many do that with simple fans in doorways and hallways. If you have a crawlspace or basement I guess you could build some sort of powered return duct system to pull cold air form the lower portions of the colder rooms for delivery to the wood stove area. I'm not sure your return on investment would be worth it though given your present efficiencies and power bill.
It may be worth trying blocking the return near the rear rooms. This would effectively create a flow of cooler air from the rear rooms to the wood stove area and increase the amount of stove heated air towards the rear rooms. However, the unrestricted return duct must be large enough so that flow into the air handler is not overly restricted.

 

[browneyesvictim]

First thought: do you have an outside air supply system installed on your wood stove? If not, makeup air being pulled in from outdoors throughout the house may be making those rooms cold.
There are many posts in the Hearth Room about "moving the heat around". Read those.
The collective wisdom there will tell you to move cold air from colder zones to the wood stove area -- don't try to move the warm air. Many do that with simple fans in doorways and hallways. If you have a crawlspace or basement I guess you could build some sort of powered return duct system to pull cold air form the lower portions of the colder rooms for delivery to the wood stove area. I'm not sure you're return on investment would be worth it though given your present efficiencies and power bill.
It may be worth trying blocking the return near the rear rooms. This would effectively create a flow of cooler air from the rear rooms to the wood stove area and increase the amount of stove heated air towards the rear rooms. However, the unrestricted return duct must be large enough so that flow into the air handler is not overly restricted.

Thank you. and I like your suggestions! Since the original post, I have in fact blocked off the return in the back and this has helped out a lot! Not perfect, but it is working! I have had the heat pump off for many days/nights now and just running the wood stove. The family room does not get as (too) hot as it was either. Best part is mama is happy!

Its funny you mention doorway fans. I have already been looking at a doorway fan to put in the hallway near the laundry/half bath and I'm sure this would help further. I just haven't pulled the trigger yet. As you walk down that hallway underneath that vent, there is a definite temperature gradient you can feel! I like your idea of a powered return duct that would run under the house.This would do pretty much the same thing as the doorway fan but without the noise and eyesore.

I don't have an easy way to do an OAK. There is an ash cleanout in the bottom back of the fireplace that would be convenient, but it comes out in the garage, and would draw air in from there which is a "no-no". I would have to punch a hole in the bottom of the existing masonry fireplace to the crawl space under the house.

Also In line with your suggestions, I have come up with two other possible ideas. They have to do with moving the warm air, but both have to do with the fixing the restricted return situation I currently have.

1.. I'm thinking of adding another return vent in the family room where the wood stove is. There is easy access in the attic to do so, for the cost of the insulated ducting and a vent and my time. This will relieve the load restriction on the air handler. While I am at it. I will probably install a gate valve to the back ducts to be closed for winter use

2. As mentioned, installing a doorway fan near the laundry room would be good, but that doesn't relieve the return restriction issue I have. Another option, but is probably a hack is installing a power booster duct fan in the return near the laundry room. But by the time I've done all the electrical for that I would have been better off with option 1.

 

[semipro]

Be sure and don't place any returns too close to your stove. That's bad practice, dangerous, and a code violation.

The cleanout may make a good outside air supply if you can link the garage end of it with the outside or a crawlspace.

 

[browneyesvictim]

Agreed!

I would be hard pressed to use the hearth cleanout as an OAK with the stove sitting on its bottom as an insert. As far as I understand the OAK can only be used if it were a pedestal mount. There is only 3 inches of clearance from the bottom of the stove to the fireplace floor. The fireplace floor is made of bricks and some can probably be removed though. I would need to yank it all out and start dismantling things to see how and where that goes. I stuffed a lot of Roxul in there when I put the stove in. I just kept stuffing, and It seemed like it took a lot more insulation than I would have thought like it went into some sort of cavity in the brickwork and never came out the cleanout door in the garage. The garage is a concrete slab, so theres nowhere to go but up.