Hooking up wood boiler to oil

[wfs]

Not sure if this is in the right place. I have a dunkirk oil boiler in my basement and run 5 zones off it. I have a feed manifold and a return manifold. Both manifolds are capped at the end with threaded cap. I want to put an indoor wood boiler in my garage and pipe it around into my house and attach it to my system. My garage is unattached and about 100 feet from where it will run into my house and existing boiler. My thought is to set up my wood boiler in the garage, run underground pray foam insulated Pex Tubing from garage to house and hook one end to the end of the return manifold and another to the end of the feed manifold. Turn my oil boiler down so it only kicks on when wood isn't keeping up or it goes out. I would have a circulator in the garage to keep the water circulating from garage to house. Am I on track or am I making it to simple?

Thanks,
wfs

 

[derek01]

I think I would set that up as primary secondary loops. Put a pump on the garage loop (primary loop) that runs continuously circulating thru the boiler feeding the secondary loops as the demand occurs. This would keep the oil fired boiler hot so the aqua stat would be satisfied when the wood is firing hot enough and as the wood drops off the aqustat would make firing the oil burner. Usually the secondary loops need to be a certain spread on the manifold but if you are fooling enough water this should work. Keep in mind each of those zones is likely circulating 3gpm so I would think you would want to be circulating at least 10gpm unless you have a side arm water heater in which case match the circulator and pipe size on the water heater loop. I would insulate the pex between the boiler and wood burner unless that heat loss is going into the conditioned space even then you may find that space being over heated. You have a relief valve on the wood burner right!! The problem with this is when the oil fires the primary circ will transfer heat back to the wood burner maybe set up so that when oil fires primary circa shuts off some how.

 

[Tractor Seabee]

Not sure if this is in the right place. I have a dunkirk oil boiler in my basement and run 5 zones off it. I have a feed manifold and a return manifold. Both manifolds are capped at the end with threaded cap. I want to put an indoor wood boiler in my garage and pipe it around into my house and attach it to my system. My garage is unattached and about 100 feet from where it will run into my house and existing boiler. My thought is to set up my wood boiler in the garage, run underground pray foam insulated Pex Tubing from garage to house and hook one end to the end of the return manifold and another to the end of the feed manifold. Turn my oil boiler down so it only kicks on when wood isn't keeping up or it goes out. I would have a circulator in the garage to keep the water circulating from garage to house. Am I on track or am I making it to simple?

Thanks,
wfs

There are many possible pitfalls with this arrangement if you are a novice at hydronic piping systems. You should consult with a very knowledgeable and experienced designer (not necessarily an engineer) as ther are several considerations such as pumps, check valves, control system changes, hydraulic seperators, proper feed wtaer piping, including expansion control, how the water flows through the boilers, and air elimination. You may have aminor problem that is not manifesting now but will be compunded when you add to the system. Most plumbers do not understand hydronics. When I was in the HVAC service businss in my younger days we wound up re-piping systems that even engineers had designed. There is proper and effecient flow patterns and then there are those that do not work or work enough to get by. There are even new thoughts on this now that can improve effeciency of old systems with some minor changes. Under ground piping that far has its own set of pitfalls and considerations too.

Old Steamfitter talking, Ron