Boiler/Water temps

[maplewoodshelby]

I just installed a EnergyKing 45ekb. This is not a gassifier but a a basic wood boiler. It is plumbed into my propane boiler which I have no intentions of using but thought I should keep it (just in case)
I have a honeywell aquastat with a lo and hi limit setting that is wired to my taco 007 pump. I also opted to go with an auto draft door (not blower) that is controlled by thermostat and aquastat should temp get too high.
My question is what should I set the lo and high limit at? It has not been real cold but I have had a fire for the past few days Lows in the 30 and highs in 40s. My water temp ranges from 115 to 150 but typically stays around 120. Right now I have the low limit at 120 and the high at 180 which it has not even got close to hitting. So basically the way my system works is that when the water temp reaches 120 it kicks on the circulating pump sending water to my baseboards. If it falls below 120 it kicks off the pump to heat up the water in the tank. My stove seems to be drafting OK and I dont have the best wood but shouldnt my temps be a little higher than this and what do other folks set their aquastats at?

 

[rowerwet]

not sure how your system is supposed to work. could the pump coming on at 120 be keeping your boiler from reaching temp?
on my system the boiler stays at 175 all the time, the circulator for the baseboards kicks off and on as the house thermostat calls for heat. the circulator is the one my oil beast used already, my OWB keeps the water in my boiler at 175 all the time.

 

[jebatty]

Does the mfr have a recommendation for this boiler? Most baseboard systems will not provide sufficient btu's at 120F, unless you have high efficiency baseboard and lots of them. The wood boilers I have seen have a hi-limit of 180-185F and a lo-limit of 140-160F.

 

[maplewoodshelby]

The manual does not say much at all about the aquastat settings. In fact I did not even hook it up when I first started running the boiler as I only thought it ran the draft. As far as my boiler not getting up to heat because my pump kicks on at 120 is certainly plausible and this temp is adjustable all the way up to 180 before the pump kicks on moving the water thru the house. However, the boiler seems to like to burn at around 120 and like I said it was 30 degrees outside and the house was toasty. Burn time of about 8 hours before the wood disappeared so that seems good. Just wandering if there are any problems associated with running the wood boiler at low temps. I know creosote may be a problem but anything else

Again my systyem is set up that the lo limit on the aquastat kicks on the pump to circulate
The high limit closes the draft but keeps the circ running
The thermostat in the house open and closes draft

 

[Tony H]

I know with my boiler the control circuit kicks the pump on at 149 F /65C and the boiler runs at 175 or so. What provides temp control for the baseboards ? Isn't there another pump that circulates water thru the baseboards ? I am not sure how your system is setup but the first thing to do is try turning up the limit to 150 and/or post a diagram of your piping.

 

[rowerwet]

from what I have read here, a water return temp below 140 will tend to cause corrosion in or on the tank, this may only be a problem for outdoor boilers though.

 

[rotaxman]

I've read the same as Rower, below 140 not good, causes condensation in the firebox. Is it possible the reason the boiler is operating at 120 is that when is gets to 120, the pump comes on and doesn't allow it to get up to higher temps?

 

[maplewoodshelby]

well it warmed up here so I have let the fire go out for now. I will set my aquastat up to 150 and see what happens. My chimney is marginal draft and I only have an auto damper on the stove. I may end up purchasing the blower that goes on teh stove in order to get higher temps. I'll keep you posted

 

[rotaxman]

well if you do give the auto damper a chance, I'd like to hear about it, ie. if you feel it doesn't get back up to temp fast enough. I'm building an OWB right now and have decided to go without the blower until I see how the auto damper allows the stove to get back up to temp. I've read that blowers, unless carefully controlled, can be hard on your wood supply. There are many variables but....
I'm currently designing my system, using knowledge from here and two of Dan Holohan's books. I plan on a supply temp of approx. 180 and return of 160. The supply will be mixed down to approx. 120 for the floor radiant. The primary system will have a bypass valve that doesn't allow the return temp to go below 140-150.
I'm just a newbie, there are pro's here that would have your answers.

 

[maplewoodshelby]

I'll keep you posted on how it goes. As of now I dont think there is anywayI can keep a temp above 160 without the blower. Like I said I have a few things working against me in a marginal chimney and not the best wood. Also the auto dammper is relatively small. I will be building a new chimney next year that will be ss insulated and taller. A blower will eat up twice as much wood for sure and just another part to break so I am trying to stay with the auto damper. If I was building my own auto damper, I would oversize the damper to an extremely large size and design it to have different opening settings. That way you give it every opportunity to draft good.

 

[rotaxman]

variable openings on the damper is a must for sure. 6"x8" hole w/variable openings that are tied to either flue or water jacket temp. maybe even variable speed blower connected to flue and or water temp would work good as well, then you could burn anything that doesn't move.