Two identical inserts, one heats well, one poorly.

[bejay]

interesting thread but my take on it is that its probably not the wood, but either the insert has problems or your flu has problems, I think you had it right in your first post if the longer flue did have a stronger draw the fire should be hotter wich would make your downstairs insert work a little better than your upstairs insert, ive read about stoves actually being more likely to overfire when the draw was excessive and its usually worse on epa stoves with some form of secondary burn because you cant close off the air to them as good.
assuming the insert is ok, I think that for some reason your upstairs flu is actually drawing better than your downstairs.

 

[Wife'nHubby]

1. Have you installed block-off plates for either insert?

Details on a block-off plate: Making a Sheet Metal Block-Off plate for a Masonry Fireplace

Reasons for a block-off plate: index | Hearth Wiki

2. Are the liners insulated?

Shari

 

[stderr]

1. Have you installed block-off plates for either insert?

Details on a block-off plate: Making a Sheet Metal Block-Off plate for a Masonry Fireplace

Reasons for a block-off plate: index | Hearth Wiki

2. Are the liners insulated?

Shari

1. I don't know. For insurance reasons (i.e. no coverage if your house burns down unless installed by a certified fireplace guru and sprinkled with holy water right after disembowling a goat in honour of our EPA overlords) the inserts were put in by professionals, and I didn't see every step of the installations. I don't recall seeing anybody cut sheet-metal pieces to fit the damper openings on either fireplace. They are sealed, but I believe the seals are at the top of the brick stack, not at the stove.

2. No. I believe some insulation is installed around the top as part of the seal, but I think that's all. I can't see how they'd get much insulation into the chimney, as the liner touches the sides most of the way up. It was quite a bear to pull both of them through.

The plates covering the original fireplace openings are not sealed at all. There are ventilation holes cut in the plates all the way up and down the sides of the inserts (not cut in the actual inserts).

interesting thread but my take on it is that its probably not the wood, but either the insert has problems or your flu has problems, I think you had it right in your first post if the longer flue did have a stronger draw the fire should be hotter wich would make your downstairs insert work a little better than your upstairs insert, ive read about stoves actually being more likely to overfire when the draw was excessive and its usually worse on epa stoves with some form of secondary burn because you cant close off the air to them as good.
assuming the insert is ok, I think that for some reason your upstairs flu is actually drawing better than your downstairs.

The only thing I can think of is when the upstairs fire is going and the downstairs is not, sometimes smoke comes down the downstairs pipe. I've read this has to do with the building acting as a better chimney than the chimney itself. When we light a fire downstairs, we can have trouble with smoke spilling into the room but it turns around pretty fast. I've noticed that with the vent wide open, the fire looks like a blast furnace. Upstairs we get these gentle looking flames licking at the top burner tubes, but downstairs we get a concentrated blast of flame hitting the window. All this makes me think the set up is OK, but there is a little too much draw and it's hard to slow it down to the point where it reaches proper temperature.

Yesterday I ran with the vent closed 50% for most of the day. It slowed the burn rate down and increased the burn-time, but I wouldn't say it was much hotter. It's -8°C here this morning w. gusting winds, so the insert has to make lots of heat to keep the place warm.

 

[Wife'nHubby]

With smoke coming down stairs when upstairs is lit, sounds like your flues are exiting at the same height and the result is a downdraft into the basement insert - not good. Solution would be to raise one flue 2' higher than the other. Do you have carbon monoxide detectors in your home?

Block-off plates just above your insert or stove allow you to retain more heat in the room space you are trying to heat.

Shari

 

[Dieselbreath]

Well, if you have cut and split your fir since Feb, it is probably good enough. I am burning fir right now that has seasoned that long. Hardwoods do take longer.

I agree about your flue heights having to be different heights if you are down-drafting from one. You can easily determine this by temporarily installing a cheap piece of chimney pipe on one flue. I have a fireplace in the basement that has this problem when I run the furnace at the same time the insert is going. There is a return register too close to the fireplace that sucks smoke down the flue. I just close the damper & it takes care of it.

Some good advice on this site but if you want additional help you should try the folks @ ********** - Information on Gas Fireplaces, Wood Stoves, Gas Logs, Pellet Stoves, Fireplaces, Chimneys and Hearth Products . There's some installers and experts there.

 

[stderr]

update

With smoke coming down stairs when upstairs is lit, sounds like your flues are exiting at the same height and the result is a downdraft into the basement insert - not good. Solution would be to raise one flue 2' higher than the other. Do you have carbon monoxide detectors in your home?

Block-off plates just above your insert or stove allow you to retain more heat in the room space you are trying to heat.

Shari

The flues are indeed the same height. I suggested that they extend the top one when installing, but the message never reached the guy on the roof. When they were open fireplaces the downstairs would fill with smoke whenever the upstairs fireplace was used. I extended the upstairs flue by just adding a 12" section of clay pipe. It worked very well. I suppose adding a section of pipe is simple enough. We do have a CO detector, but it's never complained. I'll have to pull the face plate off to see if they blocked it. I give as good odds as not that they did.

I agree about your flue heights having to be different heights if you are down-drafting from one. You can easily determine this by temporarily installing a cheap piece of chimney pipe on one flue. I have a fireplace in the basement that has this problem when I run the furnace at the same time the insert is going. There is a return register too close to the fireplace that sucks smoke down the flue. I just close the damper & it takes care of it.

Some good advice on this site but if you want additional help you should try the folks @ ********** - Information on Gas Fireplaces, Wood Stoves, Gas Logs, Pellet Stoves, Fireplaces, Chimneys and Hearth Products . There's some installers and experts there.

Interesting about the return register sucking smoke. I thought most furnaces had a separate outside feed of air with a heat-exchanger. I would never expect the intake to pull from the chimney.

Excellent site recommendation, btw, thank-you.

After running the fireplace with the repaired duct-work and sealed up fan connections for a day, I found that although there's a lot more air coming through, it's not very warm, and the glass is darkening around the edges. Today I removed the little chunks of foil-tape where the fan connects under the fire-box. The fan got much quieter, there's less air flow, but it's incredibly hot. I think it's working very much the same as the upstairs unit now.

Based on what I read on Dieselbreath's recommended site, the 40KBTU of useable output number I guessed at earlier is about right. 40KBTUs is 1/2 of the output of the gas furnace, but it's constantly pouring into the building. Time will tell if it makes a difference.

Many thanks for all the tips and good advice.