New install. Plumbing question.

[chew72]

Hello all. I'm helping a friend with a boiler install and have some questions. This is a rough idea of what I have in mind for the plumbing layout. I'm looking for thoughts, ideas and improvements. I left out all the fittings (exp tank included) and just drew in the circulators, so not to worry if looks too bare.

The boiler is a gasser and will run flat out and have return protection. Any excess heat will go to storage. That part I'm fine with. On the house side space is at a premium. The idea is to have the 130' supply/return underground pex go to a hydraulic separator. C-2 will be a Taco delta T circ set to come on full for 30 sec then maintain a deltaT of 5* across the hydraulic separator when ever there's a call for heat. To me this will keep C-2 almost matching the flow for the loads house side.

The main heat for the house is the hot air coil. The whole idea of this set up, is from a cold start the boiler can heat up and provide maxim heat and flow to the house if the storage is at say 80*F

All comments are welcome
Thank you.

PS looking at this now should C-2 be on the return side of the hydraulic separator? pushing back towards the boiler/storage.

 

[chew72]

Two more questions.
What does one do to put a dry well in the 1200Gallon propane tank. Can you make one or is it something that can be bought?
Any free/cheap software to draw a better diagram?

 

[ewdudley]

Here's my thinking on the topic:

https://www.hearth.com/talk/threads...ng-valve-to-control-loop.100419/#post-1285708

(Of course in my diagram the wood boiler is on the same side of storage as the loads, in your case it would be on the opposite side of storage.)

If you look at how they do it in Europe you'll see they like to segregate the separator into temperature zones, which works out nice and is easy to do if you build your own from a 30 gal propane tank and weld the couplings on where needed.

Take a look at how the low-temperature loads are fed. And note that you don't need a differential controller for C-2 (XFR in my diagram), just two aquastats: one that keep the top of the tank hot enough from DHW and one that keeps the middle of the tank hot enough for WAHX. C-2 does its job and the load circs do their job all independent of one another; they don't call it a hydraulic separator for nothing.

C-2 should pump away from the expansion tank connection.

 

[chew72]

Thanks ewdudley. What you said about different temperature zones got me thinking. How about drop the hydraulic separator and manfold. Instead just do a loop and use closely spaced T's. Have it run in the order of DHW, Fan coil, Infloor, snowmelt. That way the loops that need the hotter water always get it first. keep the delta T pump and set it for 20* after all the T's so only the flow needed is being supplied. Thoughts?

 

[ewdudley]

Thanks ewdudley. What you said about different temperature zones got me thinking. How about drop the hydraulic separator and manfold. Instead just do a loop and use closely spaced T's. Have it run in the order of DHW, Fan coil, Infloor, snowmelt. That way the loops that need the hotter water always get it first. keep the delta T pump and set it for 20* after all the T's so only the flow needed is being supplied. Thoughts?

There's the 'Primary secondary piping for boilers' up in the stickies, and several other relevant discussions over the years that I studied and ended up with the stratified buffer / hydraulic separator because it's simple and does the best job of minimizing return temperature to storage.

A primary loop with hottest loads first will tend to do the right thing, but if all the loads aren't drawing at the same time then you're guaranteed to be sending water back to storage that is hotter than it might have been.

My buffer tank is set up as three zones, roughly top third for DHW priority, middle third for hot loads, and bottom third for hanging on to 'spent' water from the upper two zones. As water from various zones returns to the tank, the cooler water falls to the bottom and hotter water rises to be recirculated. When any of the in-floor radiant zones are active they draw the coolest water available from the bottom of the tank.

This way the water tends to sort itself out and has a chance to stay around for a while, which increases the likelihood that it will be spent before it is sent back to storage. With a primary loop it's now or never.

 

[mikefrommaine]

I just set up my storage and have a second diverting valve for the primary loop. I had planned to use a 160-180 element in it but it has a 140-160 element that seems to be working fine. It takes the return water from the loop and sends any water below 140 back to storage and diverts any water above that back to the loop to be reused by the loads.

I thought about using an outdoor reset with the sensor on the bottom of the tank along with a motorized 3-way valve. That way I could have insured that the return water was always lower than the bottome of the storage tanks. But I like the simple approach.