Wood Boiler piping

Dan Peel

These work well with little flow restriction.

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Andy Morgan_2

Piping suggestions

I have a customer who against my advice, is buying a 600,000 btu wood boiler. He wants to pipe this to 4 different houses on his farm. In each house there is an oil boiler and small wood boiler piped to various types of radiation and for DHW. He wants to keep all of these boilers tied to the existing system. I thing the best thing to do is pipe the two small boilers and the central boiler in a P/S arrangement with flovalves, etc so that any one boiler doesn't heat the other two. I think I am going to need buffer tanks on the central boiler because one, to try to control the temp in the central boiler, and two, because there is no pressure on the central boiler and I would have to tie this to a pressurized system.

Am I on the right track here?
WHat kind of tank would you use and what make?

Any other suggestions will be greatly appreciated!

Thanks

Andy Morgan

R Morgan Mechanical, LLC

Ted_5

FlatPlate Heat exchanger

works well for this. One pump per building to feed the plate
and a pump on the other side of the plate to inject into the primary loop of the boiler in each building. To control the wood boiler from getting to hot, have a wild zone you can dump heat intoor a buffer tank.

Ted

hydronicsmike

If you want...

...you could send me what you have so far and I'll have a look at it. Sounds like you're having to be a little creative on this one. You have one centralized Wood Boiler and 4 remote buildings? Each building has an Oil Boiler and another smaller Wood Boiler? Is that right?

Sounds interesting.

Mike

Andy Morgan_2

Thats correct!

They don't want to get rid of the small wood boilers in case the central boiler goes down, or someone forgets to load it. Basically they are backing up the wood with wood, and then the oil. Very frugal people!

The newest house on the farm is only 4 years old, which I did. I hooked the wood boiler into the supply and returns of the oil boiler and ran the controls with a couple of aquastats. Now with the central boiler, I feel its just best to rip the whole thing apart and repipe as you would with multiple boilers.

BTW They are still using the original load of oil from the first fillup! As I said, very frugal people!

Thanks
Andy

hydronicsmike

Well, one should ...

...preserve. The customers are always right and we'll usually do what they want us to do.

The only time we say 'No', is when it is immediately followed by the word 'Problem'.

What do you have you could send me?

Mike

hot_rod

Consider an Aqua-therm

for the outside wood unit. These are pressurized, and as such, would eliminate the need for a HX to seperate all the exisiting systems.

The smaller water capacity, of the Aqua-therm helps speed up, and allows glycol, affordably!

Kinda would have to see the current piping to really suggest how to best intergrate them.

hot rod

www.aqua-therm.com

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Andy Morgan_2

piping

All of the boilers are piped basically the same.
The one building that I did is piped as follows:

WM GO4 boiler

1 1/4 supply to 1 1/4 x 1/2 tee for exp tank and feeder
circ,
1 1/4 x 1 tee to return of wood boiler,
1 1/4 x 1 tee to superstore,
1 1/4 copper manifold to 4-3/4 baseboard zones,

coming back from system:
4 3/4 zone valves on 1 1/4 manifold,
1 1" zone valve on 1 1/4 x 1 tee,
1" supply from wood boiler to 1 1/4 x 1 tee to return of oil boiler.

there is a circ on the supply of the wood boiler pushing water into the return of the oil boiler.

aquastat on oil boiler is being used to control all zones. Oil burner is switched off. 2 6006 aquastats run the circ and blower on the wood boiler.

I hope I made this clear enough without drawing it!

To HR, I am looking into the Aqua therm, as I am not sure if they ordered the boiler yet.

Thanks guys for your help.

Andy

hot_rod

When connecting multiple boilers

Primary/secondary is often the best choice. You want to make sure the gas fired boiler is not running heated fluid through the unfired wood boiler. If so, the wood boiler will pull heat from the gas and dump it right up the chimney. It actually acts more like a cooling tower

Also the cold wood boiler could keep the gas fired in the condensing mode for extended periods if you have them piped incorrectly.

Always pipe multiples so the unfired boiler(s) do not see flow from the "online" ones.

hot rod

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Steve Ebels

Andy

I have done dozens of these. My MO is to simply pipe a bypass setup into the return and connect a heat exchanger of the required size on the bypass. (look at the boiler piping in the pic of the Vitodens I have on the Wall right now). In the case of multiple locations, I run a main loop (primary) through all the buildings and connect a secondary pump on side "B" of the HX to the boiler pump relay to pull heat from the primary and into the HX whenever the boiler side runs. This isolates the wood boiler from the rest of the system(s) and allows the HO to go away for the weekend without having to worry about the outdoor unit freezing up. In your case, the hx's would transfer heat backward from the house side to the outdoor side and keep it from going solid on you. Not economical fuel wise but it's simple and for temporary situations not as costly as you would think. Most of these outdoor units are insulated pretty well. In the houses, how and where you would put the HX depends on how it's piped in there. Likely each one is different if there were multiple installers. I fail to see any compelling reason to maintain the indoor wood boilers in the series in the first place. For me the safety factor would dictate removing them from the picture.I'll dare bet that all of inside wood boilers are connected to the same flue as your oil boilers.

If the outdoor unit fails they can burn oil for a week while a new one is installed. What brand of outdoor unit are they going with? Do they have ANY idea how much wood a 600K boiler is going to eat? Be careful if the outdoor unit is a "closed" system. None of them are (H) stamped by ASME that I know of and as such, are not approved for use in most states. I had a Central Boiler brand that the state inspector gave us a choice of converting to an open system or removing because it was not an approved piece of equipment. No "stamp".

bob_14

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