Homeowner with Taco Products, outdoor boiler

Betz

I have a Central Boiler outdoor wood burner that I have tied into an existing system (originally gravity converted to circ.). Central boiler uses taco products almost exclusively. I am wondering if there is someone from Taco who might know how to keep this direct plumbed system from letting the cold return water back out to the boiler. I get a large temp drop and my damper opens, causing me to burn more wood than needed. I really don't think it's a problem with my house losing too much heat because the water in the radiators is fairly cool when the t-stat kicks on, which means it's not having to run all the time. The system heats great but I'm going through a lot of wood. I am guessing that I really don't need the temp to be 185, which is what they recommend because I have the old large cast iron radiators. Any info would be appreciated. I have a rough sketch of how I have it hooked up now. I'm sure the old coal converted to gas boiler didn't heat the water to much more than 125 degrees from what I'm feeling in the radiators now.

David_5

Wood boiler

If I am reading right the water goes through the coal conversion boiler all the time, and through the wood boiler and coil conversion sometimes. When it goes through both they are in series with the wood first. I have a wood boiler in my house in series with my oil boiler. What is the btu rating of the wood boiler? What is the btu rating of the other boiler? How much is alot of wood? What is the flue gas temperature on the wood boiler?
At my house the oil boiler is running at .75gph. The wood boiler is rated at 80k output. If I filled the firebox with wood at night and had no calls for heat overnight there was no wood left to burn after 8 hours. My boiler cycled at 170 - 180. Needless to say I gave up on wood.

David

Betz

taco pumps, valves, etc.

My old gas boiler is no longer in use. It's plumbed that way because that was the easiest (and at the time the only) way to hook the new boiler into the system. The wood unit is rated at 500,000 btu, i'm not sure what the flue temperature is. If my house doesn't call for heat, the outdoor unit has set at idle for over 3 days, that is, the temperature in the water outside stays at the temp i set it at, and it doesn't call for heat (opening the damper). The problem i'm having is that when my house needs heat, the cold water in my radiators goes out to the burner and cools the water rapidly and drastically. I have to think there's a way to keep the water inside the house to warm it up before it returns to the outside unit. I'm going through a truckload of wood in a week under mild temps (30 degrees). I think there has to be a way to get the flow rates right on my pumps, that's why I thought a taco rep would be able to help. The manufacturer says that using a water to water heat exchanger would reduce my efficiency, but at least I'd be separating the two loops so they wouldn't directly mix. The outside unit has a gas burner on it also, but I've yet to use it, i'm almost afraid to with all this heat loss.

David_5

Esbe valve

An Esbe valve on the wood boiler would keep the boiler above 140 degrees to protect the boiler from condensation. Danfoss sells the valve. What is the btu rating for your old boiler? 500,000 btu is a huge boiler, and makes me think it is way oversized. This would make it less efficient. If you know the water content of the wood boiler I might be able to make an educated guess about wood consumption when idle.

David

Betz

Wood Consumption

Wood consumption when idle is fine. It hold 400 gals of water and is extremely well insulated. at idle I have absolutely no wood consumption for at least 3 days. And when I do need wood it's only a few pieces. The unit is 500,000 at full capacity, which i should seldom need when everything is hooked up correctly. I can run extra pumps for garages, pools, etc., and I plan on doing at least some of that in the future.

David_5

confused

Is your complaint that you use too much wood when there is a demand for heat?

David

Betz

yes

I am getting a large amount of cold water return going back to the outdoor boiler when my house calls for heat. I tend to believe that there's a way I can adjust my flow rate so that the hot water warms the entire system slowly before it all goes back out to the outside burner.

David_5

Tekmar

Makes controls that can control the water temp in your house and boiler to do what you want.

David

Betz

Thanks

for the info. I'll look for something like that.