Plate exchanger location

Ya2UP_A

Hey all, question for the group, I had posted this over in biomass however think I may have better luck here as it is part of a radiant heat install. Not new install but retro. Bought a house that had an outdoor wood boiler and old fuel oil burner in the basement.  The old crown was replaced with a wall hung combi last year but the wood boiler plumbing all the way to the plate exchanger was left in place, I’d like to tie it into the combi now and burn this 16+ cord of wood the prior owner left me. Wanting to get some feed back on where to tap in the plate exchanger, I understand the ideal situation would be break the main return ? The issue I’m having is 1. Next to zero space for new or additional plumbing  and b.  The combi was piped in a compact close space tee continues loop, can I even put the two new tees for the exchanger in this type of configuration? And if so will it require an additional circ pump to move the water about 3 feet from the combi to the heat exchange plate?  I posted a drawn pic of what I have and a pick of what I was thinking of doing. Thanks for any advice on this!  

hot_rod

here is an option. A delta T control does the control logic. The delta t control has two sensors, so when the wood boiler is hot enough it will feed the system. set a differential for it to drop out. this makes the system fairly automatic as far as swapping between the two sources.

No need pumping thru the gas boiler, tie directly to the heat loop from the plate HX.
If you have low temperature radiant you will need a mix valve after the plate to keep from sending hot water, maybe above 180 from the wood boiler to the system.

Ya2UP_A

Thanks hot_rod!  Does it make a difference where I tap into the loop? Your drawing shows the closest/convenient  location however I do have stubs on the main return on the bottom of the gasser, I don’t mind keeping those capped and putting in two new T’s in the bend  though. Also do you have a preferred  Delta T controller? 

mattmia2

It should be in the system loop, not the boiler loop but it isn't that critical where it is in the system loop. Depending on where the air elimination is, you would want to try to get the hottest water to that.

GroundUp

As you were already told on Facebook, it needs to be repiped to the return side of the CST and the existing connections to the system loop will need to be eliminated. No additional circ. You will not get the DHW function off the OWB without adding another HX specific to DHW. If this is low temp, you'll also need a mixing valve and ideally some sort of bypass- if high temp, I hope it's a small house because that HX isn't very large.

mattmia2

GroundUp said:

As you were already told on Facebook, it needs to be repiped to the return side of the CST and the existing connections to the system loop will need to be eliminated. No additional circ. You will not get the DHW function off the OWB without adding another HX specific to DHW. If this is low temp, you'll also need a mixing valve and ideally some sort of bypass- if high temp, I hope it's a small house because that HX isn't very large.

Oh, they are trying to heat DHW, not the heating loop?

Ya2UP_A

@GroundUp “as you were already told” **** are you talking about facebook? No one’s heating DHW? If your the same kid who simply “said it’s piped wrong” which was the only reply I got to a different question that’s far different from your comment above, think you have your posts mixed up here bud.

hot_rod

A sketch of your piping would help see what options you have.
This issues explains some of the piping variations, shows wiring schematics and expl;ains them logic of using a delta T control.

Several of the systems in here I have built at my own place.
All the solar suppliers have controllers, tekmar has one. I like the digital versions from Resol, Sun Earth, and others.

It would take me a weeks worth of typing to break this down.

https://www.caleffi.com/sites/default/files/media/external-file/Idronics_10_NA_Hydronics for wood-fired heat sources.pdf

GroundUp

Ya2UP_A said:

@GroundUp “as you were already told” **** are you talking about facebook? No one’s heating DHW? If your the same kid who simply “said it’s piped wrong” which was the only reply I got to a different question that’s far different from your comment above, think you have your posts mixed up here bud.

Yes, I am talking about Facebook. That's why I specifically said "on Facebook". You asked if you needed to add a circ or repipe, and you were told pretty much the same thing that I said above by the commenters there. Your drawing literally says "DHW" on it. You are using a combi boiler, which heats DHW. IF you're going to get upset about the answer to your question, maybe don't ask the question. Bud.

Erin Holohan Haskell

Let's move on. Thank you.