Very Cold Days

First year using my wood boiler (used MidWest boiler). Everyone I know locally has forced air, so hoping someone with baseboard heat can weigh in here....

My house can stay nice and toasty (wife keeps it at 70 / 71 ) when temperatures are anywhere above the 12-15 degree range...but when it gets REALLY cold (at least, what us in Michigan call really cold) - such as below zero or negative wind chills (a couple weeks ago we were -15), my boiler can only maintain a temp of around 65-66. However, I believe the size of the boiler is more than adequate to maintain the temperature (my thermostat in the house always has the water temp at 180)....plus, it's rated at about 4200 sq. ft (double line) and my house is only about 2400 sq ft. So, I'm guessing the deficiency is in the heat exchanger OR the baseboards not keeping up. House is pretty well insulated although I know some rooms with large windows are going to get colder easier...

I still have my system hooked to the (pressurized) propane, and when I turn that on, no probs heating the house, but I know that the pressurized system gets the water temp well above 180.

I bought a 50 plate heat exchanger which was rated at more BTU's than what my furnace is rated at.

So - my question is this....is this "just how it is" with baseboard heat? Or, do I need to upgrade my exchanger....? I was thinking I could add more FLOOR RADIANT heat - since the boiler is NOT getting overloaded, it makes me think I just need to increase the surface area affected by the hot water....

Many times during the really cold spell, I'd go to reload the stove and it's still got plenty of wood, but the house is "cold". Baseboards feel "hot" so I know the water is circulating.

My other question, my indoor circultor (hooked to the baseboards) has a 3 speed setting. I currently have it on the "middle" setting (not sure exactly how many GPH that rates at)...but I was wondering, would slowing it down help? (meaning, more time to give off heat in the rooms?)

Any thoughts are helpful and thanks in advance. I love my OWB and it's saving me a ton of money, just thinking it "should" be able to keep the house toasty no matter what, so I have to tweak something somewhere!

 

I would start by setting you boiler temp to 200 or higher during these cold spells. Also check to see what the return water temp is. If it is still hot, you circulator speed is probably good

 

As long as it's sized for the heat load (enough rads), pretty hard to beat baseboard heating. If your other boiler can keep the house comfy, it's likely good - although with the HX & outdoor separation, you will likely have a hard time keeping water as hot to it as the indoor one can. So you may benefit from putting more of it in. If it was designed to just meet design heatload, at a water temp of 180 or more, then it would likely be something to consider. Adding more shouldn't be too awful bad of a job, if you can do plumbing - usually there are sections of bare piping in the shrouds that could be replaced with finned.

Could be a wide range of issues, and more info would be needed to provide much accurate suggestion. For starters, you should accurately measure all your temps in your system. For starters, OWB in & out, HX in & out on both sides, and baseboard supply & return. How far away is the boiler, and what to you have for underground piping (size & type), and what for a circulator? Temps all round should turn up problem spots.

 

Thanks for the good tips! As a "noob" to this, I guess I was being a worry wart about turning the temp up....I know the pex and everything is rated high and the only barrier is you don't want to reach beyond the 220 / steam threshhold.... I'm sure turning up the temp would help... I'll see if I can gather some more data and pass along. Thanks again for the advice!!

 

I don't think I'd run it up past 200.

 

212 is the boiling point, and you definitely don't want to make steam, but if the water is coming back cold you need hotter water. My dad used to do this in January and February with his gas boiler. Again, steam is dangerous, but 10-20 more degrees will make a huge difference. Be careful and check back to let us know how you make out.

 

Also you may need to bleed your baseboard. That can drive you crazy if there is any air in the system.

 

Well, welcome aboard, Admiral!

I also have the same problem you have...that is, cold days-OWB seems hard to keep up. Only thing is, I have forced air. My house is poorly insulated and on windy days, we don't have to worry about air exchange! That being said, when the temps hit below zero, I turn up the aquastat settings on the OWB to around 180. That's the highest I've set it, and you sure can tell the difference.
Make sure your heat exchanger from the OWB to the house hydronic system is functioning properly-transferring heat to it that is. Heat will travel from warm to cold always and will have the greatest transfer of heat when the tempertures between the two are greatest. If you house system is at 160, and your outdoor boiler is at 180, you will have a 20 difference. If your house system is at 140 with the same OWB setting (180) you will transfer more heat into the house's system.

 

How are things going with your system AdmiralKirk ? Any progress to report?

 

I have oil fired hot water boiler in the house and a Cozyburn OWB. I have the same problem, if it's really cold the OWB will only heat to 66 degrees. I put in new pex from Central Boiler and that helps with the burn time. I just think that I am trying to take more heat out of the HX than it can provide. It does help to bleed your baseboard heaters. I have had the OWB for 8 winters and tried everything. You can only pull so much heat from your boiler and HX.

 

Kid-I feel the problem does't lie within your OWB. Probably your house's insulation/sealing or more accurately, the lack there of.
You can adjust the aquastat of the OWB to get a higher temp. You can measure the line temps to find out how much of a temp drop you have by the time you get to your house. You can measure the return line leaving your house after nit has given up it's heat for the house/domestic water. The OWB is capable of producing a lot of heat. If your place is like mine, the house is capable of losing a lot of heat!

That being said, Welcome aboard! If you were to post a thread announcing your membership in "the firewood neighborhood", you would be welcomed in the true fashion of this site! Glad to have you here, and fire away with any questions or submissions/advice. And as others will say, pics, pics, pics.

 

As others have said, the only way to find out what is going on is to know what your supply and return temps are on both your heat exchanger and your zones.

 

Hello Haveissues. Thank you for the welcome and I will go and do my intro. You are right about the insulation. I have a 2800 square foot older farmhouse and this is another project. I need 25 bags from Lowes and blow it in the attic. Last summer was all work around here. Right now I am re doing a bathroom and ordered a 6 foot double bowl vanity. It should be here this week. Now I have to figure how to get it upstairs. With the install of the Thermopex from CB, my supply and return is not the problem although I wish I had bought a larger OWB. The manufacturers definitely exaggerate their BTU output.

 

I hear you about the house work. My boiler sat crated for almost 2 years before I could get to installing it. The insulation will absolutely help but if your propane boiler is keeping your house warm and your wood boiler temp is 180+ with a good return temp but still not heating the house enough there is something else wrong. It sounds like for whatever reason you are not transferring enough heat. A larger boiler will hot help that. Good luck and stay warm!

 

I'm looking into an OWB for next year as well. I have hydronic baseboard and ducted A/C with the air handler in the attic. Which heat delivery system is best for the OWB. Of course my Dad wants me to go geothermal if we can get the well water done. Thoughts?

 

So many variables involved in that decision. With the A/C being in the attic, I assume that the registers for the supply air would be a high wall? Not a good idea for delivering heated air. If that is the case, I would avoid using the air handler for heat distribution as the warm air would want to stay at the higher level.
The OWB can deliver heat to either setup....as well as being able to deliver heat to both setups (hydronic/forced air). Of course, you would have to run a supply and return line from the OWB to the attic air handler. This might not be easy.
With hydronic baseboard, the heat is delivered at floor level and can naturally convect up into the room.
Also, it wouldn't be unheard of if you had an HVAC company come over and give their opinion on the matter. So much easier o0nce you are on site to give recommendations.

 

Welcome Admiralkirk I had the same situation had my hx piped in and worked great. I reversed the flow when I added a second boiler into the loop then my first boiler couldn't keep up. If the water is flowing the same direction it will transfer heat from hot to cold fast then transfer back before the water leaves the heat exchanger thus lowering your output. If you cross connect the water (run opposite directions) the leaving secondary loop will see the hottest entering water and leave with the most btus. Also it's never a bad idea to turn up your pump speed. The more btus you can move the more you can transfer. I myself like a big flywheel. Correct me if I'm wrong about cross flow through a plate heat exchanger.