Vapor fire 100 trouble keeping up in the cold

[Spook1]

I figured I would come here for the experts and hopefully I can make an adjustment. I have a vapor fire 100 and it has been really cold here in southern Ohio. Not been above 24 degrees for several days and down near zero at night. It seems my unit has trouble keeping the house real toasty during these cold spells. I can keep it about 67 or 68 degrees but can’t get it any warmer.

My house is 2,200 square feet upstairs. My unit is in the basement but I am not heating the basement. I was getting high temp alarms pretty often a month or so ago and dale told me to adjust the damper down to like 2 or 3. That did seem to help but I will still get it when I am reloading on too many coals. My chimney is about 20 feet total in height.

I will say though that I notice my Dwyer at time showing like .15. I can unhook it and it goes back to zero and hook it up and it seems like it is where it needs to be but then later that day it is back up to around .15. What settings are you guys running your dampener? My wood is seasoned about 2 years. I actually started mixing some wetter wood in because of the high temp alarms. Any suggestions is appreciated.

 

[brenndatomu]

Did I read that right, .15?!
That is WAAY high!
I'm running 0.04 and that's plenty.
Do you have a really tall chimney or something?
Is the baro working?
Using large chunks of wood will help with the high temp alarm too, but ya gotta control that draft first!
When it gets really cold you need to rake those coals forward an hour or two before loading to try to burn them down more, but keep them off the front firebox panel.
You can add a couple real thin splits or low btu wood (like pine) to the pile to help make more heat (but not add to the coals) while they burn down some.

 

[brenndatomu]

Do you have the computer turned up? How much?
Do you know what species of wood you are burning? Some coal more than others for sure...oak, locust, hickory come to mind.
Lower btu woods that many people turn their noses up at are nice to have around for times like this to add to the fire for more heat during coal burn down times...

 

[Spook1]

Yes I have the computer turned up high.

I think there must be an issue with the Dwyer. . I can unhook it and it go to zero. Add wood at it be a like .04 where it needs to be for a long time. But when I go back 8 hours later to reload it is always then that high. At that point my unit is on 3 and needs wood added.

It is just I didn’t remember the Dwyer doing that last year. So something threw me with it this year.

 

[sloeffle]

I think there must be an issue with the Dwyer. . I can unhook it and it go to zero. Add wood at it be a like .04 where it needs to be for a long time. But when I go back 8 hours later to reload it is always then that high. At that point my unit is on 3 and needs wood added.

It's a pretty simple piece of equipment, my guess would be there aren't any issues with manometer. Not unless it's been dropped etc.

Assuming it's at the end of the burn I would suspect that the chimney has warmed up and is pulling more draft. When you cold start your furnace, it basically has zero draft (zero on the manometer), the further you go along in your burn, the more draft it has because the chimney is getting warmer. The chimney is the engine of the furnace.

Do you have a barometric damper?
What's the reading in the middle of the burn?

 

[Ladarian]

Are your 2 heat exchanger pieces installed? I had to take mine out because it was putting out to much heat for us.

It's been single digits or lower for over a month and we rarely put it above half its been on lowest setting for 85% of the season.

We fill ours maybe 3 times a day so we have it pretty scheduled. Never load overnight on a large bed of coals (says as much in the manual)

Do you have a cold air return setup?

Picture of your setup?

 

[Spook1]

yes the heat exchangers are in place. I figured the Mano was just changing at the end of the burns. Makes sense. It is where it needs to be with a fresh load put in.

I will post more pics of the setup when I get back to the house. My stack temps seem to get in the higher 400s and close to 500 when it is reloaded. Lowers down to lower 300s after it gets to the lower c setting.

My cold air return is connected in with the cold air return for the rest of the house.

 

[brenndatomu]

Wow, I've seen situations where the draft might surge to double the normal baro setpoint momentarily during a wind gust, but never triple, and sustained!
Those Dwyers are dead simple, if they are zeroed, plumb n level, they are accurate. (Assuming it has the red gauge oil in it)

It did recently have an issue with mine where it was reading falsely low...I usually check zero at the beginning of the burning season, but I forgot, and was having issues with setting the high alarm off, when it shouldn't have been.
Turns out the gauge was low on oil...which is weird because it hasn't moved one millimeter, and there was zero sign of an oil leak. Topped off the oil, zeroed it, all better.

 

[brenndatomu]

Also, when did you last clean your heat exchanger? (HX)

I clean at least twice, sometimes 3X/yr.
I can tell when it's time by monitoring the flue temp vs the supply temp...when the flue temp is 50* higher than normal during pilot burn (c) then I know its needed. I try to start the season clean, then hit it again in early January for the inevitable January cold snap, then sometimes again in the spring, especially if we have a long drawn out spring heating season.
I've found (and I think the other Kuuma owners will agree) that 2 things dirty up the HX, running hard, like computer turned way up, especially for days on end, and a long drawn out shoulder season, with lots of cold starts...or at least "no coals left" reloads.
I've made myself a couple tools that make cleaning the HX a bit easier...just a wide putty knife that I can scrape the area I can reach, then a long handled scraper with a steep angle, so that it can go between the HX tubes to clean back behind.
It makes a difference!
That's the thing that SBI has a superior design on is how the HX gets cleaned on their furnaces...so quick n easy, it can be done in 2-3 minutes, wearing dress clothes, and not get dirty!
No reason not to do it every week...oh, and it can be done hot!

 

[Spook1]

I have just cleaned mine before the heating season. I will try that and see if it helps. I am hoping that is the case. I did do several cold starts back in December just bc of the weather.

Here are a few more pics I just now took. The Dwyer reading was when I first went down to add a couple of pieces of wood to take the chill off. After throwing a few pieces in it dropped down more than half in just a few minutes as the draft started back up on the reload. So it may just be that it rises that much as the blazing fire dies down, but I didn’t remember it being like that last year. I also included a pic of where my Dwyer is connected in and a pic of my complete setup. Any other suggestions are appreciated.

 

[Spook1]

Here are the pics.

 

[brenndatomu]

That is really strange...

 

[Dieselhead]

I’ve had the piece of tubing I have inserted in the stove adapter plug up with creo and the manometer will act the way your describing.

 

[JRHAWK9]

yes the heat exchangers are in place. I figured the Mano was just changing at the end of the burns. Makes sense. It is where it needs to be with a fresh load put in.

I will post more pics of the setup when I get back to the house. My stack temps seem to get in the higher 400s and close to 500 when it is reloaded. Lowers down to lower 300s after it gets to the lower c setting.

My cold air return is connected in with the cold air return for the rest of the house.

Nice. You are monitoring temps. Having temp data helps a lot.

I'm assuming the temp circled in red is plenum temp? What about the one with the arrow pointing to it? Return air temp? Do you use the stat to switch the Kuuma blower from low to high when it calls for heat? My house did not heat very well when I had higher volumes of lower plenum temps; like with how the blower system comes from Lamppa. I had to slow my blower down to get my plenum temps higher. I now run plenum temps between 100° (temp when the blower shuts off) to 137° and the blower is speed controlled. The hotter the plenum temps are, the faster the blower turns. Made a -HUGE- difference for me, but not all houses heat the same and what is optimized for us may not work for another. Our house is very inefficient and loses a lot of heat.

I've found (and I think the other Kuuma owners will agree) that 2 things dirty up the HX, running hard, like computer turned way up, especially for days on end, and a long drawn out shoulder season, with lots of cold starts...or at least "no coals left" reloads.

yep, I'll also add excessive draft to that list, as that seems to carry more fly ash into the HX area. Now that I am running mine back on low, it is now running ~100° over what it will do with a clean HX. It needs a cleaning BAD. I have not cleaned it this year yet. Have not had outside temps that would allow me to shut it down long enough to have it cool down in order to do so.

Are your 2 heat exchanger pieces installed? I had to take mine out because it was putting out to much heat for us.

I'd just load less wood vs blowing more BTU's out the chimney.

 

[Spook1]

I will take it out and clean it and see if it is what is causing the mano issue. I am hoping cleaning the heat exchanger will help with the heating issues. It seems like my stack temps are pretty high or higher than last year. But I didn’t right that down and don’t know. Any reason would happen? It seems like I am sending a lot of heat up the chimney.

It just seems like I should be able to heat my house to 70 degrees with it but I realize it hasn’t been above 25 so maybe I am wishful thinking.

 

[JRHAWK9]

It seems like my stack temps are pretty high or higher than last year. But I didn’t right that down and don’t know. Any reason would happen? It seems like I am sending a lot of heat up the chimney.

A dirty (fly ash coated) HX will do that for sure. The fly ash insolates the metal and limits heat transfer resulting in lower plenum temps and higher flue temps. I have it going on right now with mine.

It just seems like I should be able to heat my house to 70 degrees with it but I realize it hasn’t been above 25 so maybe I am wishful thinking.

Extended cold snaps are tough. Heat loss is exponential.

 

[Spook1]

Nice. You are monitoring temps. Having temp data helps a lot.


View attachment 345930

I'm assuming the temp circled in red is plenum temp? What about the one with the arrow pointing to it? Return air temp? Do you use the stat to switch the Kuuma blower from low to high when it calls for heat? My house did not heat very well when I had higher volumes of lower plenum temps; like with how the blower system comes from Lamppa. I had to slow my blower down to get my plenum temps higher. I now run plenum temps between 100° (temp when the blower shuts off) to 137° and the blower is speed controlled. The hotter the plenum temps are, the faster the blower turns. Made a -HUGE- difference for me, but not all houses heat the same and what is optimized for us may not work for another. Our house is very inefficient and loses a lot of heat.



yep, I'll also add excessive draft to that list, as that seems to carry more fly ash into the HX area. Now that I am running mine back on low, it is now running ~100° over what it will do with a clean HX. It needs a cleaning BAD. I have not cleaned it this year yet. Have not had outside temps that would allow me to shut it down long enough to have it cool down in order to do so.




I'd just load less wood vs blowing more BTU's out the chimney.

The smoke shows the stack and plenum temps. The little white gauge just shows the temp in the room and the humidity.

I haven’t done anything with the blower. It is set just how it comes from the factory. I have it wired to the thermostat and it set on 72 but I don’t get to that temp in the house. So I assume the blower is just kicking on high.
Can you explain this a little more. It seems like this could help.

Our house was built in 2012. It is well insulated. But I am on a hill and we always have wind which could cause some of the draft issues for the chimney. But should be able to heat pretty easily.

 

[brenndatomu]

I’ve had the piece of tubing I have inserted in the stove adapter plug up with creo and the manometer will act the way your describing.

Good point...I clean the tube end and my stack temp thermocouple every couple weeks.

And yes, I tried using the factory setup as far as the thermostat/blower high speed thing...nope. Turn that thermostat off and let it run on low, see how you like that...

 

[Spook1]

Good point...I clean the tube end and my stack temp thermocouple every couple weeks.

And yes, I tried using the factory setup as far as the thermostat/blower high speed thing...nope. Turn that thermostat off and let it run on low, see how you like that...

Can you tell me what I need to do for that? Just unhook the thermostat? Or do I need to switch something on the unit as well

 

[brenndatomu]

Just set your thermostat to "off"
Or I guess you could just set the temp down real low so it never calls for heat

 

[JRHAWK9]

yes, start by just running the blower on low. See if that helps you any. It's running the blower on high if the stat is calling for heat. Like Bren, that did not benefit me either.

 

[Spook1]

So if just set the thermostat to say 20 degrees, the unit will automatically just run the blower on low and in theory will run more often? I don’t need to change anything on the actual furnace itself? Sorry for the dumb questions.

 

[brenndatomu]

Correct

 

[Spook1]

Thanks guys. I appreciate your help more than you know. I will report back in a few days.

 

[brenndatomu]

Probably has nothing to do with it, but your furnace filters aren't plugged up, are they?
If the blower has been running on high, and the filters were plugged, they'd likely just be collapsed anyways.
I get by with one set per year...