Bought a Wood Boiler. Help with plumbing diagram & control schematics?

[SIERRADMAX]

I placed a deposit on a 1 year old econoburn 100 and I'll be picking it up in a couple weeks. I want to get the schematics down before the unit arrives so I'm ready for install.

My current setup is an oil boiler feeding three zones. One being an indirect water heater. The house is 2600 s.f. heated by two hydro-air units making up the 2nd and 3rd zone, respectively. The existing boiler diagram can be seen with the attachment.

Power is supplied to the L8418 Aquastat which I assume acts as the primary controller. From there it controls the circulator pump on the return line and burner. What's suprising is there's no low voltage wiring from the zone valves to the aquastat so how would this trigger the boiler to turn on?

With the addition of the wood boiler, do I have to add a bypass connecting both the supply & return headers so the wood boiler primary pump doesn't create a dead-head situation? If needed, how would this affect the oil boiler's operation in the event the wood boiler is not in use. I intend on installing a set of valves to isolate both boilers for servicability and summer use.

Also, If I do have to install a bypass, would I have to rewire any of the controls so the oil boiler doesn't turn on when the wood boiler is in use. If the wood boiler primary loop is connected to the zone headers above the oil boiler, wouldn't there be stagnant, cold water in the oil boilers supply riser triggering the oil boiler to fire?

 

[mikefrommaine]

You can use an aquastat that breaks on temp rise (on the Econoburn) to break the tt connection on your oil burner. That way it won't run if the Econoburn is up to temp.

And you can add a pipe connecting the existing headers to create a primary loop. Then add a couple tees and check valves to plumb in the Econoburn.

 

[mikefrommaine]

http://www.woodboilers.com/images/stories/documents/woodboilerplumbingschematic1211.pdf

 

[danjayh]

You can use an aquastat that breaks on temp rise (on the Econoburn) to break the tt connection on your oil burner. That way it won't run if the Econoburn is up to temp.

And you can add a pipe connecting the existing headers to create a primary loop. Then add a couple tees and check valves to plumb in the Econoburn.

If you want something that's even cheaper than the aquastat, get a strap-on snap disk that breaks on temp rise and put it on a pipe somewhere. Run the econoburn 20 degrees warmer than your oil boiler, and get a snap disc that closes 5 degrees above the oil boiler's setpoint. This solution will cost you around $10. If you need a link to an appropriate snap disc, let me know and I'll send one along. This is the solution that I used to shut off my propane furnace when the wood boiler is running ... works like a charm.

 

[maple1]

Please post the snap disk link - I'm considering that for my sidearm control.

 

[danjayh]

Please post the snap disk link - I'm considering that for my sidearm control.

I got my snap discs from Senasys. They have a wide variety of options with various mounts with almost any temperature option you could need. I put a few specific links in this thread a while back: https://www.hearth.com/talk/threads...-furnace-wood-boiler-freeze-protection.93110/ ... I just didn't want to keep posting more links because I don't want people to think I'm a salesman They're just the only ones I could find who had all the different temperature and open/close on rise combinations that I needed. Also, they're fairly cheap and made in the USA, which are two things I like!

 

[SIERRADMAX]

The plumbing diagrams from woodboilers.com indicate a 'swing type" check valve over a weighted check valve to be installed in the pipe connecting the existing headers. What is the difference between the two?

 

[mikefrommaine]

The swing checks use a metal flap that swings up and out of the flow. Weighted checks use a weight.

Weighted

http://www.pexsupply.com/Taco-Flo-Cheks-276000

Swing

http://www.pexsupply.com/Check-Valves-Swing-Check-3000

The weighted checks are more expensive but will stop ghost or gravity flow. The swing checks wont stop gravity flow but will keep water from flowing backwards through the system.

 

[SIERRADMAX]

I think I understand it now. When there isn't a demand for heat (i.e. no zones open), swing check is open and wood boiler pump circulates water through the primary loop. When a zone opens, it closes. So, why not the use of a weighted check valve? Is it just because of the price difference?

 

[SIERRADMAX]

Econoburn's bypass and Primary loop diagram indicate the use of two pumps. A bypass pump to go on with the boiler and off at 150, then the primary pump to turn on 150. Isn't a single pump with a diverting valve better at preventing cold water from entering the boiler? I would think that when the primary pump is energized, the stagnant cold water in the return line will be cold.