FIreplace Insert Heat Distribution (Duct through ash dump?)

[kd129806]

Hello All,
longtime lurker. Created an account today.

I have a fireplace insert, which I bought used, and installed myself (with fire marshal inspection).
My house is 26' square, 1940's 2-story, open floor plan downstairs, with a stairway in the middle to 2nd floor bedrooms.
Masonry chimney and fireplace located on north side of the house.
The house has a forced air gas furnace, and the ducts can be adjusted independently to tweak the heat distribution for each room.

The stove is a mid-2000s lopi revere, and I did a fully insulated re-line of my 24' chimney.
Once we started burning for the winter, I put a box fan on the 1st floor, kicked up the insert's blower, and wired up the central furnace to continually run the blower on its low setting, kicking the gas on at 60F or less.
We started heating with it in November, and it definitely cranks out enough heat for the house, re-loading every 6h or so on black locust.

I have 2 problems for which I'm consulting the tribe.
1. Even with the box fan and the central blower going, the living room (10x26) is about 85F to keep the rest of the house at 70F.
2. I'm going through more wood than I expected. If I go outside and touch the backside of the masonry, it is warm to the touch.

I have several proposed solutions that I'd like some feedback on.

Problem 1: The existing masonry fireplace is rather large, and so is the ash dump. The stove has a hollow air jacket surrounding it, which is 1.5" off of the firebox ( for circulating room air). I'm entertaining the idea of running a return air vent to my central furnace, directly from that air jacket. Since the ash dump is large enough and accessible, I'm thinking of running a 4" or 6" duct through it into the basement, to tie it into the furnace. This would reduce the heat output of the stove into the living room, and increase the heat output directly into the rest of the house.
My proposed plan is to cut a hole in the air jacket around the firebox (just behind the face plate), and draw air out of it using regular galvanized steel duct work.
I know the stove manufacturer would almost certainly not approve for liability reasons.

Problem 2: I'll be installing a block-off plate in addition to my full re-line. I have some sheet metal handy, so it's free. I'm afraid that I'm losing some heat up the chimney (around the outside of the insulated liner) I'm pretty sure this is kosher.
I'm considering insulating between the masonry and the stove using roxul. I've heard of others doing this without issue, and I can't see any problem with it. The manufacturer has no masonry-stove clearance requirement or anything, so they are certainly not depending on any air-cooling here (the outside of the stove here is the outside of that steel air jacket).


Feedback
Can anyone think of a reason why these proposed solutions would be bad ideas? I am unwilling to accept paranoia, but I will accept rational arguments. Can anyone think of a better idea for improving my heat distribution?

 

[begreen]

It is against code to tie the stove into the central air system. Altering the insert in this manner would certainly void insurance coverage.

You may be getting a lot of duct heat loss in the basement. Try working with nature by turning off the furnace blower. Cold air is heavier and easier to move so reverse the plan. Use the box fan to blow cool air into the stove room. Place the box fan on the floor facing the stove room, from as far away as possible with the entry to the stove room still being in line of sight. Run the fan on low speed. You should see about a 5+ degree increase in the cooler area and correlating -5 degree drop in the stove room temp within 15-30 minutes.

 

[mellow]

Kill the idea of tying it into the ductwork, against code and would more than likely not work.

Absolutely insulate that fireplace, you are seeing the same thing as many others with exterior fireplaces, all that heat is going to the back and out, roxul is OK but with Micore or Durock is even better, see my thread on install ideas: https://www.hearth.com/talk/threads...lating-my-fireplace.75755/page-2#post-1635483

Between installing the block off plate and insulating the fireplace I think you will see a big difference in heat output, I know I did.

As for the stove room being hot, no way around that, it is going to have to be hot in that room to get warm air circulated to register at the end of the duct work.

 

[Vespers]

Some installers in my area use Roxul to seal off the area between the smoke shelf and the stainless liner to act as a block off plate. This is a lot easier than making a custom fit metal one. A large amount of convection is happening if you leave that open. I used Roxul in my Pacific Energy Vista insert install and also used it to insulate the back and side walls of the fireplace opening all the way up to the smoke shelf and the Roxul block off.

Mineral wool melts at 2400F and does not burn, as it is volcanic rock fiber. If any doubt remains, use ceramic wool which is used inside fireboxes. More expensive, but you and your insurance company may feel better, as Roxul is not Code nor approved for that use.

I also insulated the outside of the masonry chimney on the level where the insert is installed.
Talk to your insurance company and if they seem okay with what you are doing follow up in writing and keep a copy. Mine was more concerned with me knowing what I was doing than with code or WETT inspections.

I have been thinking on similar lines as you and have run into the Code thing also. I want to tear open the fireplace opening in the basement and install a wood stove with ducting moving the heat to the back of the house. I have electric heat and no existing ductwork, so the ducting will be for the wood stove only. I have yet to run the idea past my insurance company, but the Building Code in my area will not allow it.
See my thread on this, here:
https://www.hearth.com/talk/threads/free-standing-stove-inside-masonary-fireplace.136601/