Seton not keeping up

Well, hard to say.......there are a couple factors at play.
Given the temps and the winds right now, heat loads are going to be really high!

As to not keeping up, there are some fairly scientific formulas regarding flow in heat exchangers - it might be that you are pumping the water through the HE too fast, or that the furnace fan speed need adjustment. Some others here might be more schooled on the particulars, but it is not as simple as anything goes.

What do your water tubes look like? Do you know what your stack temp is when your fire has been cranking for a while?

I've got a Seton 130 and I can go easily 16 hours on a load of wood even with 0F temps outside. I have a 3300 sq ft 2 story house and we keep it 72F.

Not sure what could be wrong, but your definitely loosing a lot of heat somewhere by the sounds of it.

Pat

Size of your supply and return piping? More info the better for all to try and figure out your problem. In a detached building... Home sq. ft...

Actually if the water is moving too slow it will give up its heat too soon and pass a fair amount of poorly heated air. The water flow should be fast enough to allow for a 20* f drop from input to output of the HE and no more. You should be using 1" pex for the supply and return 3/4" could work if the boiler is fairly close to the building being heated. 1" is a safer route. If you are not getting the flow you need an obstruction (lime in your water or gunk from the system?) or an air bubble could be the culprit. My EKO40 is plumbed with 1" pex and two Taco 007's that run 7 up to 11 gpm (according to the advertising) with little head pressure. My house is probably smaller than yours but my sytem peaks out at around 178*f and at 140 the furnace blower works a long time. At 160+ we get pretty good results but last year, after re routing some plumbing, I couldn't get heat with max temps until I put enough pressure on the system to force a bubble out of the HE.

If the boiler was working last year then I would check for air in the system. I had to run mine to 25# before the bubble moved and heat started to flow from the HE. Be sure to bleed the pressure back down once you clear the bubble out. 1" pex is pushing for a 300' total run but it's being done. If the boiler is burning right and there are no obstructions anywhere in the exhaust then I think you are right about too small of a boiler. In my EKO40 I'm getting 8-10 hours with r ed oak and 10 -11 hours with white oak and hickory and still have a real good coals base. My house is only 1700sq ft and the EKO40 is rated for more than 2x that and I get a lot of idling in warmer months. In the winter with reduced blower capacity it doesn't idle very much but still enough that "storage officionados" would cringe but I am not able to do storage yet so I work with what I have.

I put a manual bypass switch on my supply pump so the pump runs 24-7. (one pump for the boiler itself and one for the dhw/house) I really don't understand the "reduce your pump flow concept" and would crank your pump up until I got the heat I needed. 165*f water should heat the air enough for you to get heat in the home. Forced air limit switches usually kick in at around 140 and if you are getting air that warm out of your HE then you "should" be getting the heat you need. In another thread there was a situation where the answer was a better HE (thicker with more water coils). With todays jumps in electricity I am paying about $20 more per month but I am not paying $500+ for fule oil. That goes a lone way towards "green" ($$$).
In any event it still sounds like you will need to go to a bigger boiler if you want to add in the shop. Econoburn might be a good choice if you want American made. I could't find one when I bought my EKO and with reg's being what they are I would go with the cert's and be done with it. As far as sizing I went "bigger" based on fuel consumption and loading times and have not really been disappointed.

Something isn't right. I don't think it's a size issue. I have just over a mile of 5/8" radiant tubing in floor and in concrete. I'm heating close to 9000 sq. ft. I have a homemade Seton sized between a 130 & 180. I can open all 16 zones, have both injector pumps running full speed pulling from my boiler loop and the boiler will keep up. Last night at 10:00 I put four 10" rounds of dead ash in with an outside temp of 9*F. This morning at 8:00 there was still some heavy coals left with my loop temp at 160*.

My Seton W-100 delivers far more heat than my 18"x20"Hx can remove. I suspect the same is true of your W90.

If the problem is that the boiler is undersized for the load, then it should be running wide open without cycling. If the boiler is cycling on and off without delivering enough heat, then the problem has to is do with your system not being able to remove and use the heat fast enough ( look for air bubble as Cave2k suggests, undersized lines, undersized pump, flow obstructions, etc. )

I would guess you have fly ash build up in the outlet or stove pipe.

you could calculate, or maybe you know your primary loop gpm, x delta t [ cold return to boiler/ hot supply out of boiler]x 500= btu heat output produced by boiler and size that against the rated boiler output. example, 13gpm - 20deg delta t x 500=130kbtu/hr being extracted from boiler, if the rated output is = or less you might be correct on a undersized boiler, if it is truly clean, 500 deg flue seems high

1” pex for both lines. About 150’ away from house. 2400 sq ft ranch I have not checked this year but it was around 22 degree drop last year at the exchanger. Everything is still pointing me to a size issue of the boiler. For this to get a 8 hr burn at best it would have to be a 50 degree day

Click to expand...

I think you need to investigate just how much heat you can push through 1" PEX on a 300' round trip + fittings, valves, and so on. At some point, pumping harder and faster will top out at the zone of diminishing returns. You can only cram so much heat across such long distances through 1".

Lot of such tales of woe on this forum

RickH said:

When the house is caling for heat the boiler runs wide open and struggles to maintain 150 degree water. I would think it should be able to cycle if it was large enough or at least maintain a higher temp. The entire stove was cleaned out about 1 month ago with the normal ash buildup. I should clarify that when installed new last year it struggled to maintain the heat and would run constantly. Filling it 5 plus times a day on a mild day is not practical or efficient. Thanks for the input.

Click to expand...

I agree, Rick. The fact that it's running wide open and can't hold steady temp tells us that the pumps and piping are moving all the heat produced plus some. So the problem is not air bubbles, weak pump, or small lines. I think we're down to three scenarios: 1) boiler is operating inefficiently 2) heat is being lost somewhere 3) boiler truly is undersized for the application. Here's some thoughts:

1) BOILER NOT OPEARATING EFFICIENTLY - based on enerything you've said, you got good wood and fairly reasonably clean tubes, this does not seem to be the problem. Could the rear tubes badly fouled? Have you checked them?

2) HEAT IS BEING LOST SOMEWHERE: I suggest that you trace the whole boiler loop to gather current water temperature data while under full fire for
a) leaving the boiler
b) into house
c) into forced air hx
d) out of hx
e) into/out of backup boiler (if it applies)
f) leaving house
g) return at boiler
I think this is important to so you know exactly where all the heat is being given up. Maybe there's more water in the ground since you measured it last and you're losing more heat there?

3) BOILER IS TRULY UNDERSIZED
a) do you have a backup fossil fuel boiler? Do you have any data on avg btu/hr? Or can you let the house run off of it long enough to calculate some heat consumption (ie 100,000 btu/hr boiler runs 45min/hr is roughly 75,000btu/hr )
b) do you have a calulated heat loss for the building?
c) IF everything is working right, I think the boiler will probably deliver about 60,000, maybe 70,000 btu/hr max to the house. How does that compare with a) and b)?

my 2 cents

Sorry to hear your woes Rick. This is NOT a good time to have heat problems. Going to be cold all week they say.

I know ABSOLUTLY NOTHING about HX into a warm air furnace. I recomend ya heed wat Caldwell says on that front.

On the wood fired unit . . . two questions . . . .

Did you say it had trouble keeping up last year?

Set the aquastat higher (I am currently running at 190 with a 20 degree swing) and load correctly (reasonably dry hardwood rounds half way up the door) and see if it can hold when the damper opens

My system worked fine until I did a replumb and got air in the system but I knew I had air when the boiler would get up to temp and the house kept cooling down as it had been working. So if that is not your problem then either pex size or boiler size is probably where the trouble lies. Unfortunately going to a bigger boiler may not help "IF" the pex size is not able to carry the load so be sure you check that out before you put in a new boiler. It would be terribly frustrating to have a bigger boiler and still not get the delivery you need. As old and poorly insulated as my house is I question if my EKO40 would give me the results I am getting with an added 700 sq ft without going to a commercial sized HE.

Undersizing you can't "fix" right now, so leave that out of your analysis.

Not trying to be argumentative here, but . . . some posters have wanted to finger the PEX size. . . . the OP said that when the heat load hits his hydronic, the hydronic can barely make 150. To me, he is getting PLENTY of heat transfer to the house. Maybe too much. For now, concentrate on getting the Seton to hold at a minimum 180 deg. Then go from there.

EVERYONE burns 'good' wood. But I can tell you that many times my first year my GW ran the same way. Constant strugle to keep temps up. Rarely a problem now that we're burning 90% oak