Adapting wood stove to baseboard heat

zdelles6913

I am looking into the possibility of moving my woodstove to my basement and adapting it to work with my oil boiler for baseboard heating. 

My thought is to add a heat exchanger to the back of the stove (there is a 2 inch or so gap where the blower pushes air up toward the top of the stove) and possibly adding a coil around the stove pipe then feeding preheated water to the oil boiler, using the pump on the loop to push the water through the baseboard heat in the house, and return back to the stove. 

Hopefully resulting in more efficient heating of the house, and less fuel oil usage. Another positive factor would be having heat in the basement as I currently do not have any heat at all other than wood stove in living room.

Curious if anyone has accomplished something like this, and what sort of issues I may run into. I'm having a difficult time searching anything close to what I have imagined.

Thank you for any insight. 

hot_rod

There was a time when some of the wood stove manufacturers offered hydronic kits to attach to the outside, for DHW or hydronics. Probably a combination of little market and liability, you don't see them anymore.

It is still somewhat common to see hydronic components on the stoves at European shows.

The main issue is the control, you need somewhere to dump the hydronic heat if the wood fire is burning but there is no hydronic zone calling. it's not easy to quickly ramp up or down a wood fire, safely at least.

Ideally an over-heat function that could still work if the power went out. Thermo siphoning to a buffer tank installed above the stove is a simple option, not always doable in homes, however.

Another concern is pulling too much heat away from the stove and getting creosote forming issues.

No doubt it can be done safely, but solid fueled appliances do take a bit of interaction, you need to be around to tend them, adjust the burn, clean them, feed them dry quality wood, etc. With a hydronic add on, that adds more babysitting to the task.

SuperTech

I would look into a wood burning boiler designed for that purpose. A buffer tank is a must have for baseboard systems, the larger the water volume in the system, the better it is for temperature control. The wood boiler can be installed outdoors and connected with a plate heat exchanger, if an outdoor wood boiler is still allowed in your area. Baseboards, panel radiators or cast iron radiators can be added to the basement. Definitely want a dedicated venting system for the wood burner. I'm sure some other more knowledgeable members will have some more to add.

psb75

DO NOT install a water coil around a wood stove flue. CREOSOTE FORMATION will occur. Also I have not seen any external i.e. outside of the firebox heat exchangers that were effective. I have installed inside-the -firebox stainless steel pipe (horseshoe shape) heat exchangers. The woodstoves were 1970-1980s vintage. They all had a heat-storage tank that operated by thermo-siphon with properly installed DHW TPR relief-valves. Only copper piping for the plumbing i.e. NOT PEX on the stove thermo-siphon loop.

Mustangman

I have some real mixed emotions about wood boilers assisting an oil boiler. A good fellow plumber friend of mine hooked up a heat exchanger inside a fire place for his friend. When he installed it, he must of got confused and forgot a relief.... check that, he had a relief but in the wrong spot. It exploded and there were people in front of the fireplace. His wife and daughter got severe burns. His friend sued the hell out of him. He never told me what they settled for. I have to assume, millions.
I have installed a few over the years. They just never seemed worth it to me. Don't get me wrong there are a few good wood boilers out there and as long as you follow the directions to the letter, you will be fine. Just be careful
Steve

psb75

Installing one of those in an open fireplace is "sketchy" from the get-go. Installing the right TPRV in the right place in the right manner is always critical--in every application. In a thermosiphon set-up there should be TWO of them: 1. near the heated "coil"/exchanger, just outside the heating appliance and 2. another at the storage/buffer tank.