Connecting my Tarm Solo 30 to existing oil boiler

[MasonWoods]

Hi,

It has taken me 2 years to get around to installing this thing. It's time to get it done. I have been reading posts and doing my homework on and off for too long. I have been playing around with so many options as far as connecting it to my existing system that I just could not decide on the best approach. In the end I think the attached is how I plan to go about it. Can anyone give me feedback on this? Am I making any terrible mistakes? I am trying to make use of as much as possible with what I already have in place. Given that I don't have time to tear everything apart and start from scratch.

I don't currently have storage but would like to plan it in to add later if possible.

Comments?

 

[MasonWoods]

Hopefully a clearer image..

 

[Chris Hoskin]

because you have the indirect water heater there is no reason to keep your oil boiler hot with the wood boiler. This gives you unnecessary standby losses that you will want to avoid especially once you have added storage. Please give me a call or PM so I can send you our drawing "Solo 2". Works great, no need to second guess what will work.

 

[MasonWoods]

I didn't plan to run this through my existing boiler. I don't believe this would happen with the way I have it drawn up. I have seen many diagrams on this forum I like more than what I have but I don't want to start over from scratch.

Main goals with this are 1) to avoid running it through the oil boiler, 2) I don't want to start over. I prefer to make use of what I have which is fairly new. 3)Keep it as simple as I can for now to get it up and running.

 

[Chris Hoskin]

just thought I would post what I sent you today so others could comment too:

In looking more closely at your drawing, you are right that with the check valve in place you will not pull (much) through the oil boiler. That being said, with a check valve there AND in the orange line, your C3 pump (between the Termovar and the wood boiler) will dead-head when there is no call for heat. This will likely result in ghost flow past the check valves in your zones and/or through the oil boiler and will be hard on the pump. The easiest solution is most likely just to eliminate the check valve in the orange line so that flow will go there when there is no call from the zones. Assuming you are going to use pressurized storage eventually, the tank will take the place of the orange line and should work quite well.

 

[MasonWoods]

That makes sense. Do I still have another problem? Lets assume I install pressurized storage where the orange line is. How will a zone know where to draw from if the wood boiler is not running? It could draw from either the storage or oil boiler or both.

 

[ewdudley]

Since your system is zoned with pumps, the biggest problem I see down-the-road with storage is that you may lack the ability to control return temperature to storage, assuming all those pumps are over-sized and will move a lot of water with low deltaT.

What you end up with is a scenario where storage starts out at a high temperature, and all the water takes a lap around the system every hour or so, losing 10 or 20 degF each time through. At some point you have a tank full of not-so-hot water that can barely heat effectively, whereas if water is drawn out of storage as slowly as possible then water would be returned to storage as cool as possible and you end up with more heat having been extracted, effectively increasing the size of storage.

When you're zoning with valves you can use a variable speed circulator with constant pressure or outdoor reset control that will minimize return temperature, but when zoning with pumps you should consider using closely-spaced tees or a hydraulic separator to isolate the main load loop, and use a separate pump and control to feed heat in from storage (or the wood boiler until storage is put in place). So without storage the wood boiler would feed into the load loop with closely spaced tees or a hydraulic separator, then with storage inserted the storage would feed in where the wood boiler used to, and the wood boiler would feed storage.

Also it might simplify things in the long run to isolate the oil boiler with its own pump and closely-space tees to feed the load loop, which probably easier said than done depending on how things are arranged currently.

Google for the words 'wood' 'water' and 'Seigenthaler' and pull up the article 'From Wood To Water' an look it over, especially part 2. It's a lot of pumps, but that may well be necessary to do it right.

--ewd

 

[Rory]

I have an oil boiler, a Solo 30 and unpressurized storage. My oil boiler was reconfigured with a setpoint controller to heat storage if it drops below wherever I set it. It works great, I wouldn't change a thing.