Adding a Panel Radiator with Pex

Redrum

The background. Jump to last paragraph for the question

First, this is my initial question on the subject: https://forum.heatinghelp.com/discussion/comment/1680900#Comment_1680900

The rest of the background - I have a Buderus boiler with 5 zones - first floor, upstairs, hot water, basement, and porch.

The original piping was 1" copper, and there is a 1 1/4-1 1/2? supply and return "manifolds" at the boiler.

I replaced all of the baseboard (main floors - first, upstairs) with new baseboard which is 3/4" copper, so it's reduced. The hot water tank was piped 3/4". The porch is a small panel radiator piped 1/2" copper, reduced near manifolds.

The basement (900 sq ft) is existing 1" finned, with the sheet metal enclosures, rusted and shot. I am planning on replacing this with a one or two panel radiators, or a panel radiator with fan (Toyotomi). Their fittings are 1/2".

For the basement, without heat it might get as cold at 58 F in the dead of winter (western new york). I only use the existing baseboard to bring the temp up to say 60 or 62 when I am down there working. So, the heat just needs to bring the temperature up a few degrees.

So (finally) - I am going to repipe the basement zone to a new radiator. I plan on a 1" - 1/2" copper reducer -> 1/2" sweat ball valves (with drain) -> 1/2" to PEX fitting, 1/2" pex (o2 barier) to 1/2" shutoffs at the panel -> NPT of the panel.

Because I am super careful (paranoid), I am wondering about the 1/2" pex, and if the 1/2" pex fittings (barb inside pipe) would constrict the flow (copper fittings do not constrict, as they are outside the pipe). I am wondering if this is ok, or maybe I should consider 3/4" pex, then reduce to 1/2" at the shutoffs at the panel

Jim

hot_rod

A cast radiator or panel radiator?

1/2" pex should be able to handle 1.5 gpm easily. So running at a 20° delta that would get you 15,000 BTU/hr.
With pex you shouldn't need many fittings, maybe two ells where you come out of a ceiling or floor joist space.

It comes down to how much heat you are trying to move into that space. If it is a cast radiator, obviously 3/4 pex could move more flow= more radiator output.

Redrum

Hi Bob, panel radiator. Thanks for your help, and for the flow/btu specs. 15k/hour is more than enough headroom. I was just looking for reassurance that the pex fittings would significantly restrict the flow.

Jim

Ironman

What piping method is feeding the BBs now: series loop, Monoflo, direct return, or reverse return? And what method are you planning to use for the new panel rads?

If it’s presently a series loop, then chocking it down to 1/2” or placing panel rads in series is not a good idea. Also, if the system is zoned with zone valves and not circulators, this zone could be starved for flow since water takes the path of least resistance.

Buderus has a panel rad installation manual that shows different piping methods and the valves needed. I can’t attach it from my phone, but I’ll try and post a couple of pages tonight. Or, you could try googling it.

psb75

Uponor fittings have the best flow numbers of most of the pex fittings on the market.

Redrum

I wish I knew how to get email alerts again, where did that check box go?...

Hi Bob;
I don't know the lingo, but the supply manifold supplies the flow to each zone in parallel. Single pump. The return manifold has the zone valves on each return just prior to the return manifold.

Each of the "runs" are series loops - example: for main floors - supply ->rad1->rad2->...rad n->zone valve->return manifold.

For the hot water, and the porch panel radiator (just one), it's there and back.

Planned for the basement, there and back to the toyotomi 190 I am considering, or, maybe 2 panels, piped in series or parallel, not sure which is right, but haven't gotten there mentally as I'll probably buy the toyotomi https://toyotomiusa.com/product/hc-190b-toyotomi-heat-convector-with-wall-bracket/

The tototomi seems most appropriate because with a fan, it can be more of an on demand heat (like when I go into my workshop for a couple hours).

Hope that helps the understanding
Jim

PS - I am the "whoosh" guy from a couple years ago (one zone closing while others remain open), never got that solved, just live with it. Strangely, it happens very rarely now

hot_rod

If you have a large header/ manifold at the boiler you should be able to tee in another zone valve. Consider a delta P circulator, it would assure adequate flow as zones come on and off

Ironman

Here’s some diagrams from the Buderus manual. A simple direct return would suffice.

The pressure bypass valve is not necessary if you use an Alpha delta P circulator like hot rod said.

Redrum

Sorry guys, I composed this yesterday and thought I hit "post". I didn't:


I already have a zone and valve, I am replacing an existing 1" copper baseboard run (that works) with 1/2" pex to a panel/convector because the baseboard sheet metal is shot, and I want to get things off the floor.

My question really was that of adequate flow rate (which you answered Bob, thank you) using pex.

It's really a simple change to my system. Currently, I have about 16' of baseboard (1" copper with aluminum fins) whose enclosures have been destroyed over 30+ years by moisture. When I bought the house in '91 it had a "finished basement" (concrete floor) until the water started creeping out. I ripped out the walls and studding to expose the problems and the drain tile and wall cracks will be fixed next month.

In the process, I moved the electrical outlets from 15" to mid wall fed via conduit from above. Similarly, I want to replace the baseboard radiators with a single wall unit (Toyotomi looks bet for "on demand"), and adapt the 1" copper to 1/2" PEX.

So I was just being cautious regarding flow rate in 1/2" PEX vs copper (copper fittings are outside the OD of the pipe, pex is inside the ID).

This also isn't as critical of an installation as we might make in our homes. I am just looking to be able to "warm up" the basement in the dead of winter a few degrees "on demand".

Sorry for all the info, but I thought I would let you know my motivations

Jim

Redrum

while I am at it, a little off topic, but whenever I have added a zone, I add ball valves with drain on the supply and return. My thinking is to be able to isolate that zone if needed without taking the system down. I use the "drains" that are mounted up high to vent the lines allowing them drain. Make sense?

So I will be adding 1/2" ball valves (per original post) unless it is better to use say 1" or 3/4" ball valves and reduce after.

Ironman

Again, please consider that water takes the path of least resistance. If you only have one circulator and other zones with larger piping are open, you may not get sufficient flow to the zone with 1/2” piping. This is why we suggested adding a separate circulator for this zone.

A 1” pipe carries 4 times what a 1/2” line does. You’ll be greatly changing the the flow dynamic with the smaller line.

Redrum

Ironman said:

Again, please consider that water takes the path of least resistance. If you only have one circulator and other zones with larger piping are open, you may not get sufficient flow to the zone with 1/2” piping. This is why we suggested adding a separate circulator for this zone.

A 1” pipe carries 4 times what a 1/2” line does. You’ll be greatly changing the the flow dynamic with the smaller line.

understand completely. However, per my OP, I already have a 1/2" run that heats and maintains temp fine, even when other zones are open. Both the present (porch) and new (basement) I consider "secondary/non critical". I don't sit in either. The porch is more of a mudroom in the winter (take boots and coats off) and the basement is either laundry or workshop. If the 1/2" zones have to "wait their turn" any temp fluctuation is of no consequence. But, so far there isn't.

I do appreciate 100% your advice, and if I was, say adding a living space, I certainly would be more careful in the design

Thank you;

Jim

Peter_26

I think the Toyotomi you are considering has a high resistance at 1.5 gpm and I think panel radiators are restrictive also. The basement is going from 1" baseboard to 1/2" piping which adds even more restriction. I would take the suggestions of the professionals and add the pump.

Alan (California Radiant) Forbes

I'd like to see you do it without the pump. I think it would work. (Please see tag line below.)

hot_rod

I would give it a try also, as you suggest. If the panels under-perform or take too long to heat you'll need to choke down the other circuits, or zones.

In a perfect hydronic world, all multi circuit pumped systems would have a balance valve. With a software like HDS you could calculate all this.

Probably 90% of installers of pumped or valved systems have no idea of them actual gpm in each zone under various load conditions Even ECM circulators with gpm readouts lie.

But even manual balance valves on each circuit will cause over pumping as zones close down, the circulator just keeps running up curve.

Auto balance valves would "nail" every circuit gpm exactly with a fixed speed circ.

I still feel the delta P circ does the best job of keeping all circuits getting the correct flow.
Just need to decide on how good is good enough.

Alan (California Radiant) Forbes

I think that first screen shot should say "Delta-P Circulator", not "Fixed Speed Circulator", no?

hot_rod

Alan (California Radiant) Forbes said:

I think that first screen shot should say "Delta-P Circulator", not "Fixed Speed Circulator", no?

3-24b? Not labeled are the pressure independent balance valves on the right side of each fin tube.
They keep the flow rate in each circuit stable, but run the fixed speed circ up curve as zones shut down, which lowers the gpm.

You are correct a delta P circulator is even a better option with PIBVs. It would look more like this

Redrum

Peter_26 said:

I think the Toyotomi you are considering has a high resistance at 1.5 gpm and I think panel radiators are restrictive also. The basement is going from 1" baseboard to 1/2" piping which adds even more restriction. I would take the suggestions of the professionals and add the pump.

Quoting just Peter, but thanks to all for your input. One thing to remember (see my OP) other than the basement that I am changing, all zones are 3/4" max. There are no 1" runs. The main zones were choked down from 1" to 3/4" because, while 1" was original piping, when I replaced the baseboards, they were all 3/4" weil mcclain slant fin (I believe). So current zones are 3@3/4" (up, down, hot water), and one at 1/2" (porch panel), and the basement (rarely used) is 1" but soon to be 1/2". So, there are no 1" zones, just 3/4" and 1/2"

I'll look up what circulator I have a little later today. I remember changing it during my "woosh" work (other thread) but changed back because the newer pump was very noisy

Jim

Peter_26

Got it, for some reason I thought they were going to be kept 1".

Alan (California Radiant) Forbes

@hot_rod Those screen shots are hard to read. Only a portion shows up and you don't get the whole picture. Wish there was a better way.

hot_rod

Alan (California Radiant) Forbes said:

@hot_rod Those screen shots are hard to read. Only a portion shows up and you don't get the whole picture. Wish there was a better way.

I'll add the Idronics issue # and page that they come from. All the above are from Idronics #8 Hydronic Balancing

Redrum

my circulator pump is a taco 007-f5. I have a grundfos ups 15-58 FC pump sitting around. If I remember correctly, The Taco was the original installed by the contractor. When I added the 1/2" zone, and the "woosh" became apparent, after allot (pages of posts) of consult from this forum (thank you), I showed the thread to my contractor and his attempt to address was to swap in the grundfos. (I think) my system went from whisper quiet to noisy, and it didn't help the woosh. I could hear the pump running in the living space the floor above the boiler (a whine), so I switched it back in the summer.

I don't think that either are a delta P circulator. What would be a good one to try? The house is about 1700 sq ft of living space, the boiler a buderus GA 124.

Like I said, I think I just got used to the woosh. To summarize, it occurs (most apparent) when a 3/4" and 1/2" zone are open, and the 3/4" zone closes. I have taco zone valves. I can actually manually create the noise/turbulence when I manually close the zones at the valve. One the the forum members also thought if I went back to the honeywell style valves it would solve the issue.

Not that I care that much, but if a delta P circulator is best for my setup, I'll be happym to change it out.

Ironman

Grundfos “Alpha” is a delta P circulator, which means it modulates based on pressure differential.

Redrum

hey everyone, thank you for commenting, I appreciate it, and I know what to do. I went to my local plumbing supplier to get a couple 1"-1/2" copper reducers, and a couple 1/2" ball valves yesterday. I got ready to be surprised at the cost, but wow...I can't imagine the bill for those of you doing a complete install with copper. Maybe it's not being used that much anymore?