Hpex to panel radiators

pex fan

Thanks for the reply. I think i'll plan on running 3/4" Hpex from the boiler closet to the 3 other closets (sends and returns ~40ft ea.), hook them up to manifolds, and send 1/2" Hpex to the radiators from there (sends and returns).

Ultimately, I'm having a plumbing/heating contractor hook all of this up but I find that if I do all the dirty work ahead of time it saves me lots of $$ not to have to pay 2 guys to crawl around my attic.

If the Hpex lines run through the attic (currently uninsulated but it will end up with ~2ft. of loose fill) should I insulate those lines with foam sleeves?

Thanks for your input.

pex fan

Hpex to panel radiators

I was interested to read this article in the "Hot Tech Topics" section of the site because I am trying to figure out a similar system:

"Each panel radiator connected to the manifold with supply and return lines that were tiny by American standards. Water flowed continuously between the boiler and the manifolds. The boiler had a reset control to monitor the outdoor weather temperature and change the supply water temperature to the manifolds. Each panel radiator had a thermostatic radiator valve that the occupants could set to their comfort needs. The water that flowed to the manifolds would move (or not move) through the panel radiators as the TRVs modulated. The differential-pressure regulators in the near-boiler piping pretty much nailed the circulators on their performance curves.

This was a wonderful mix of constant flow with variable temperature (on the boiler side of the manifold) and variable flow with variable temperature (on the radiator side of the manifold), and it was so simply done. The system was fine-tuned to both the outdoor and indoor conditions and this is pretty standard piping in Europe. I think we can learn from their use of manifolds. We use them in America for radiant, sure, but I think manifolds are well worth a closer look when it comes to radiators, especially if we start to use more panel radiators....I was looking at his panel radiators and asking how the water flowed into them. They were set up on a one-pipe system. I couldn’t see how the water made it from the pipe into the radiator. That’s when I asked if they had some sort of Monoflo tee going on inside the pipes. I made my sketch. He told me that the water flowed into the panel radiators because the pressure drop across the pipe was greater than it was through the panel radiator. The tees were spaced widely – the width of the panel radiator. Oh.
Gil Carlson used to say, “When two piping circuits are interconnected, flow in one will cause flow in the other, to a degree depending upon the pressure drop in the piping common to both.” That’s the basis of the Monoflo tee, and also of primary-secondary pumping."

Anyone designed/installed a system like this? I'm trying to figure out exactly how the Hpex is run from the boiler to the manifolds to the radiators...

Thanks.

Ted_9

Panels

Buderus and DiaNorm have nice application manuals.

Mike T., Swampeast MO

With one-pipe, TRVs are usually a retrofit.

New systems using TRVs should be two-pipe if at all possible. The diminishing supply temperature does not allow the TRVs to be fully independent as they are with two-pipe systems.

pex fan

hPex and radiators

I think two lines (supply and return) to each radiator makes sense inculding the valves on each radiator. I looked at Buderus' manuals but they don't touch on the idea of remote manifolds. Any ideas on how this might work?

This is on a 3rd floor of an old Victorian. 2nd floor has it's own system in the basement. We're thinking of installing a small wall mount unit in a 3rd floor closet. We don't want to run individual supply and return lines to each radiator (11 total) from the boiler in the closet but are thinking of running 3 or 4 3/4" lines to remote manifolds which would then feed 3 radiators ea. using shorter 1/2" runs of PEX.

ALH_4

Remote Manifolds

I have done that many times, and it's absolutely the best way to install the piping. I dont know why more heating contractors do not do it this way. The only drawback is that the service guy has to get into a closet or other out of the way location to access the manifolds.

Unknown

insulation

Definitely insulate all supply return lines going to radiators and manifolds, no point losing heat where it's not needed.
I've done several such systems for customers as well as in my own home, as Andrew said it baffles me why not more contractors are doing it this way, works excellent in retrofit situations: fishing 1/2" pex up old duct cavities to the 2nd floor is a snap!

pex fan

pex system

Makes sense to me. Now, onto the heart of the system. I've got 3 solar hot water panels I want to put on the roof, connect them to an indirect tank (like a SolarStor Contender SB), and use a small, wall-hung boiler (like a Munchkin MC50) as a back up heat source for the indirect tank. The solar obviously heats the domestic hot water via heat exchanger #1, and the Munchkin would back-up heat the domestic hot water via heat exchanger #2. Is there a way for the solar to also bring up the input temp of the boiler water? Or is this not that big a deal with a boiler that efficient?

Thanks

Bob Bona_4

I would

recommend a pex-aluminum-pex product like Fostapex or Multicor for this application. Regular pex grows and moves at an alarming rate as it gets hotter. Noise, chafing, abrasion, stress results.