Replace low hanging black steel pipes with Pex tubing in homerun config to radiators?

Project42day

Input anybody? We are trying to make the "right decision". 1936 home. just removed original converted coal to natural gas boiler and expansion tank. The radiator heat system has been awesome for34 years we have lived here. We will be installing a high efficiency gas fired condensing boiler plus a few heat pumps for some a/c next year. 100% asbestos abatement just done. The basement pipes are freshly painted with all asbestos removed. Hubby wants the small gain of ceiling space with a spaghetti dinner of Pex. Wife is conservative and old fashioned, energy conscious. Worried that this might compromise the formerly perfect radiator system. Pex or original piping to the radiators above? Save a marriage!

Jamie Hall

So far as the heating is concerned, switching to PEX will not make much difference -- PEX has a little less flow resistance than iron, so you might be able to drop one pipe size on the mains, but not on the laterals.

However.

PEX has a quirk: when it's warm, it's floppy. In a heating application like yours, it needs to be continuously supported in a metal trough -- you can't just hang it from the joists, even every joist, never mind at odd intervals like iron or steel. So... you may not gain much headroom, if any -- and, in my opinion, it will look a good deal worse.

Steamhead

Not to mention the cost. Leave the pipes as they are, and insulate them with fiberglass.

hot_rod

If you are talking a pex system homerun, 3/8 & 1/2" pex is workable. Possibly several radiators on one set of pex.

If you are up for it, the tubes could be drilled thru the joists and be covered with a ceiling

Refer to a joist drilling schedule for spacing of holes.

leonz

Please show us a picture of the boiler and piping at the boiler.

What Jamie and Steamhead said, leave it as is and insulate the pipes or just leave them exposed as the basement and floor above the piping will be warmer.
If you have standing column radiators as it appears from the basement view using pex to replace the existing pipe will be a waste of time and your good money.

hot_rod

I suppose if one goal is to finish the basement for additional living space, which increases the value and resale value, it may be worth moving pex lines into joist space. Walls are insulated and furred, you are part way there

Looks to me you gain at least 6" in some areas?

Have you priced fiberglass insulation for all those lines$? Insulation boots for the ells and tees?

Project42day

Update, the wife won! We are keeping the black steel pipe for the new installation. That also gives us $ 12,000.00 for other projects and warm floors on the main floor. We will determine what (or if) to wrap them with during this first heating season. The pipes will remain as a quirky old house feature in the basement family viewing room we envision. I will report back to this thread when the cold weather arrives and the new boiler system is installed. Had there been any problems with the original system we might have been more open to further change with PEX. Imagine for 34 years, annual inspection and not a single problem with a cosy, totally silent, balanced, gravity fed system! Fingers crossed the new boiler will live up to the original. We are in Niagara Region in Canada and tried all summer to secure an LG trained technician to install an LG Multi VS with Hydro Kit so we could say goodbye to Natural Gas. We worked with the main LG supplier for our area (O'Dell Associates) to find a qualified tech to do the job, to no avail. We had technicians not even show up, "ghost" us, or back away (due to so many lucrative new multiunit residential and commercial projects). Winter is coming, We gave up and will remain with a new IBC SL 14-115G3NG natural gas boiler with an indirect hot water tank. We'll do the ductless heat pump/minisplits for a/c next year. That will give us some "shoulder season" heating flexibility as well. Thanks to all who posted replies.
,

SuperJ

IMHO you made a good call. Good heat pump technology does exist (popular in Europe). But in NA equipment and contractor options are limited. In another 5-10years I suspect the landscape will have changed. Residential mech systems are too much of an investment to be an early adopter and be plagued with long standing issues.
Re the LG HP, you could contact GPA in Toronto https://gpainc.ca/ (Distributor not dealer for LG). They may recommend a dealer. I've worked with them commercially (I work for a commercial controls contractor). But, I think you'll have a better heat pump experience in a couple years.

Teemok

Good boiler choice. A secondary reason to re-pipe would be new zoning. I might have considered running individual radiator supply and returns or group zoned reverse return branches of pex-al-pex (not floppy and expands similar to copper) routed above the ceiling back to a manifold circulated by an ecm secondary pump. If sized correctly you would never know the difference performance wise and if flows were balanced right with outdoor reset and start boost used you might get better efficiency and responds times. I do like to see the old pipes still doing their thing though.

hot_rod

In addition to picking up more user friendly basement space.
A home run system could provide room by room zoning with TRV or actuators on the manifold. A 37W ECM circ would cut power and probably heating costs by zoning the system.

With a mod con you could ship the mix valve shown in this example.
Just saying.

Project42day

Update! Hot-rod, you work with Caleffi. We used a Caleffi SEP4. The project is in. The black pipe looks "retro". The heat is absolutely lovely, including the radiant effect on the hardwoord floors on the main level. Comfort in the large basement room is excellent. 2 Smith Kickspace heaters in our kitchen are now on a separated loop with a dedicated circulating pump. They are working beautifully. Moving to PEX is still enticing... something for a future owner to worry about. A/c and shoulder season supplemental heat using minisplits will be for 2024 budget. Once we resolve our bimetallic corrosion concerns at a few joints, we will be all set. (a separate thread on this forum) Thank you folks for your invaluable posts.

hot_rod

Great looking install. I like seeing the steel piping painted.
Grazie for the Caleffi parts.

Project42day

Update here. Our first winter with this new equipment has been wonderful. We were very comfortable all winter. The operation was very quiet. The hottest temperature of hot water maintained even for the deepest baths and the busiest kitchen. We used an Ecobee thermostat. It will be tough to assess any savings on the gas bill because this winter was not typical. last summer, we also replaced all the windows in our home. That has surely contributed to greater comfort. Thanks to those who posted here. I am moving to minisplit questions next.