Econoburn and Radiant heat

[gradwell]

I have an Econoburn 150 that I use exclusively with in slab radiant tubing. No storage. My question is that I know it is suggested to run the low set number at 160 deg., but being that my design calls for only 95 deg. temps, this 160 deg. setting seems excessive. If I lowered it, would I sacrifice boiler efficiency, or would I actually improve my situation? I figured I could run the low setting at 135 and high aquastat at 165. Would this cause excessive idleing? Let me know what ya's think and thank you.

 

[NNYorker]

Do you have anything to monitor your return temp. I keep my return temp. 150* min. with a set temp around 168*. I raise the set temp depending on weather conditions. I idle as I have no storage. Return temp is a big deal for these units-too low temp will decrease life expectancy. No idea on your radiant situation- sounds like mixing valves, etc. ,etc. Someone here with much more knowledge than me will reply.

 

[mtnmizer]

Is this with a wood boiler set alone or in series/parallel with another boiler?
It's easy to stall a wood boiler with a slab radiant system. There's a lot of variables
to look at. I can for example bring the wood boiler up to 190 degree idle with a full load
in the firebox and within 45 minutes have the temp down to 150 and needing a reload.
At that point the slab is "fully loaded" heat wise..

A point to keep in mind that if you have a primary loop that the EB feeds into it's
possible to have too cold of return water by the way the EB system is engineered..

MM

 

[gradwell]

Thanks NNyorker, I do monitor returns. My circ. pump is between supply and return making my return temps about the same as supply temps. with no mixing valve. I know that return temps are important and should remain above 145 and closer to 160. I just didnt know if this return temp. is relative to top end temp. numbers. So in my scenario of lowering my low and high set numbers, would this permit a lower return temp..

Mtnmizer, My unit is a stand alone. Havent had return issues yet, and I think the worse is over. When the slab was cold (about 40 deg.) I was concerned about that but now I am just about to design temp. so I hope not to see a large heat dump in any particular zone.

 

[heaterman]

You want to keep the water temp fairly hot (150*+) on any boiler of that type to avoid excessive creosote problems and prolonged periods of low fire. Use a 3-way mix valve or injection mixing to drop the temp for your slab and let the boiler run hot. It will work better for you in the long run. The LAST thing you want to do in any wood boiler is run water temps so low that the flue gas condenses. Not a good thing.

 

[Gooserider]

Thanks NNyorker, I do monitor returns. My circ. pump is between supply and return making my return temps about the same as supply temps. with no mixing valve. I know that return temps are important and should remain above 145 and closer to 160. I just didnt know if this return temp. is relative to top end temp. numbers. So in my scenario of lowering my low and high set numbers, would this permit a lower return temp..

Mtnmizer, My unit is a stand alone. Havent had return issues yet, and I think the worse is over. When the slab was cold (about 40 deg.) I was concerned about that but now I am just about to design temp. so I hope not to see a large heat dump in any particular zone.

You need to maintain an absolute minimum return temp of about 140°F at all times, except when the boiler is first getting started and the entire unit is cold - you then want to get it up to that minimum as quickly as possible. It is no problem to have a return temp that's above the minimum from a boiler health standpoint, but the lower the return temps the better the efficiency as long as you stay above the minimum. The output temperature, and how much ΔT you get going through the boiler can be adjusted... (In theory the boiler will transfer the heat most efficiently with a high flow rate and minimal ΔT, but that can be less desirable on the other end of things)

Gooserider