Opinions on new piping scheme

dave123

So after a lot of back and forth, I've sketched out a diagram of the piping for a proposed hot water heat system for my (older) home. Pic below. Three zones based on common heat loss rates, taking into consideration some of the physical limitations of the house. These would be new rads, with TRVs but also isolation valves to do a bit of balancing. These are all direct return; the only zone that could be (somewhat) easily piped home run would be zone one. Just the main floor rads are shown; zone 1 is above a heated basement, zone 2 above an unheated garage, zone 3 is partly above both. Just looking for some initial feedback. Thanks.

Big Ed_4

No it is all wrong

Intplm.

What has made you decide on this two pipe system?

dave123

Intplm. said:

What has made you decide on this two pipe system?

You mean as opposed to all home run? All of zone 2 needs to be placed in or on the ceiling of the unheated garage, so home run would mean a lot of the ceiling of the 700 SF garage would need to come out and be replaced, or all run on the surface, where there's already lots of obstructions. Zone 1 could be home run, but the pipes of zone 3 are already pretty short.

What piping arrangement would be preferable?

hot_rod

A reverse return would be a bit more "self balancing"
A delta p circulator with the TRV would help assure correct flow as the valves modulate.

Intplm.

dave123 said:

Intplm. said:

What has made you decide on this two pipe system?

You mean as opposed to all home run? All of zone 2 needs to be placed in or on the ceiling of the unheated garage, so home run would mean a lot of the ceiling of the 700 SF garage would need to come out and be replaced, or all run on the surface, where there's already lots of obstructions. Zone 1 could be home run, but the pipes of zone 3 are already pretty short.

What piping arrangement would be preferable?</blockquote



I was just wondering if you had considered a series loop system? Like this ? But with the circulator on the feed and not the return as shown......Pumping Away .

dave123

Intplm. said:

dave123 said:

Intplm. said:

What has made you decide on this two pipe system?

You mean as opposed to all home run? All of zone 2 needs to be placed in or on the ceiling of the unheated garage, so home run would mean a lot of the ceiling of the 700 SF garage would need to come out and be replaced, or all run on the surface, where there's already lots of obstructions. Zone 1 could be home run, but the pipes of zone 3 are already pretty short.

What piping arrangement would be preferable?

What would be the advantage of a series loop (all one zone?) over the 3 zones with two-pipe?

hot_rod

If you series loop heat emitters each downstream emitter sees a lower supply temperature, that would need to be calculated to assure adequate heat in each room. With panel rads, 3 maybe 4 per loop depending on the radiator size, ∆T you are designing around. There is some math in here to help with lower SWT adjusting.

https://www.caleffi.com/sites/default/files/file/idronics_25_na.pdf

You have a few choices for piping as you know. Diverter tee, home run, series, parallel as well as various return piping options.

It comes down to what you or an installer finds to be the best method for the application.
It could be based on ease of installation, structural restrictions, zoning options, cost, type of radiators, installers skill, multiple temperature zones, etc. All have pros and cons, some are better for specific applications.

Looks like you have a blend of parallel and series going on.

dave123

I think the only segment that is series is the short pipe between the two baseboard units, which will run through the wall between the two bathrooms. The rest should be parallel direct return.

Was just looking to see if anyone could see any obvious oversights. If there's flow meters on the zone returns at the boiler, then the only potential problem I see would be the more distant rads being short-changed on flow, if the TRVs don't cut it in really cold weather. And that could be fixed by adding a few balancing valves, correct?

I could change zone 1 to a remote manifold though, and home run from there.

hot_rod

If you go with TRVat ever radiator and a delta P circ, it should work fine. TRVs work regardless of cold weather:) They are responding to the temperature at the TRV, not outside, as is the radiator.

With fixed speed circulators on multi zoned, multi emitters balance valves are used to fine tune, assuring best heat distribution and most efficient operation. It may be a bit over-kill for a small residential project. No harm is adding valves to the various zones for checking and confirming flow rates, like a 132 Quicksetter.

TRVs and variable speed ∆P circulator, ODR boiler control should get you a very nice system, possibly constant circulation once dialed in properly.

To me an ideal system would be a boiler and distribution that continually modulates to ever-changing loads. Modulating boilers, TRVs and ∆P circulators can get you very close to that operating condition.

dave123

But the system as diagrammed, especially zone 1, runs the risk of the early rads taking too much flow and leaving the last ones with too little flow, doesn't it? On the coldest days, presuming the TRVs on the early rads are wide open, that's going to rob the end rads of enough flow, no?

Tinman

My recommendation would be a home run distribution system using 1/2" Pex-Al-Pex, manifolds with flow balancing capabilities, Delta P pump, TRVs.