Multitude of Questions

[menoche]

Hello folks,

This is my first post, and it's probably going to be a doosy. That said, I've read quite a few posts and this appears to be the place on the web to ask these types of questions. I thank you in advance for your help.

My current situation is as follows.

I have an existing, running Weil McLane hot water furnace for the three zones in my home. I purchased a used 20+ year old Jensen wood (and possibly coal) burning boiler and I would like to install it to offset my oil useage. I would like the situation to be fairly simple, such that when there is an existing and acceptable amount of heat available from the wood burning, that it simply reduces the need for my oil furnace to fire. Sort of a 'dumb' setup vs. my having to choose a mode of operation, change a valve position, etc... I am hoping you folks might suggest possible ways to hook this up, and help me assess what I have. Jensen is long out of business, and US Stove, the last purchasers of the assets, do not have a manual or schematic for this unit. I am having to make assumptions as to how this is hooked up as a result. I am aware of several options, including the use of liquid/liquid heat exchangers, single and triple aquastats, etc... but I am hoping someone with a better grasp, and personal operational experience with a combination system may be able to give me some pointers. I could also use help identifying some of the components, as described in my photos. Last, if anyone has a manual for this type of unit, I would be very anxious to get a copy. This could be an email with a PDF, a fax, or scanned file, for which I'd gladly pay the reproduction costs.

Thank you. I look forward to the insightful comments that the members of this board are known for.

John



(broken link removed)

 

[webbie]

Aha, one of our members here works at Preston Trading Post in CT, and they certainly would have a manual for that unit!

That is stoveguy13 .........he'll probably be along shortly. If not, you should PM him. They probably have parts also - and, yes, these were coal boilers also - with optional grates.

Besides asking questions here, you should get a hold of another manual - that for a TARM add-on boiler (stoveguy may have one of those also).....or ask Eric here (see EKO has landed thread in "Gear" if the manual for his boiler addresses some of this.

There are two generally accepted types of installation - those being in series or in parallel.

I often used the parallel approach. Works like this....

Take water from the oil boiler with a small circ to the wood boiler and then back to the oil boiler.

Controls - turn down the oil boiler to about 150. Have a control on wood boiler which turns the circ (above) on at 180 and off at 165...or something like that. Also have "overheat" control which jumps house zone in case boiler hits 195 (approx).

That should get your started......

 

[menoche]

Thank you Craig, that's a good start. Now, by being parallel, do you mean I should use a heat exchanger to add heat to the return water on the oil boiler, keeping the water loop for the wood boiler isolated? Or, are you suggesting taking some percentage of the return water from the oil boiler, diverting it through the wood boiler then adding it back again? If it's only a portion of the return water, would you use a mixing valve with controls, or simply a fixed valve position? Maybe I should wait till I get the manuals...thx - John

 

[webbie]

That method refers to circulating water between BOTH boilers when the wood boiler is hot, therefore having a decent storage of heat - the house then works to take care of itself as needed (from the existing thermostats). So picture the wood boiler as just another "burner" adding temperature to the water.

The series method entails installing the wood boiler in the return BEFORE the water gets back to the oil boiler - but for many reasons it is not suggested with relatively low water volume (less than 45 gallons or so) boilers - mostly because of the boiler getting too hot too quick when there is no call for heat.

On that subject, you might consider adding a 4-way mixing valve to your largest and most used zone, which will do you a LOT of good with both oil - and especially with the wood. It effectively adds the water volume and the mass of the house radiators to your storage. You should find some old threads here with pics - and it is also in the Tarm manuals. I should scan some of those....but I don't have them! One day soon I am going to visit Preston and they agreed to allow me to scan some of their (thousands of pounds) of archived stove materials......

 

[webbie]

See this thread on the mix valve:
https://www.hearth.com/talk/threads/6219/

and this wiki article:
https://www.hearth.com/econtent/index.php/wiki/4_Way_Mixing_Valve/