What size pex to add baseboard

[Taylorjm]

So I have hot water baseboard heat with three zones. The basement, bedrooms and main floor. The baseboard in the master bathroom is connected to the bedroom zone. We keep the bedrooms cooler for sleeping so I want to change that baseboard to the main floor zone otherwise the bathroom is freezing. It's all 3/4" copper piping. If I were to use oxygen barrier pex for changing that baseboard, what size can I use? I know 3/4" pex with crimp fittings are restricted a lot when compared to 3/4" copper and 1" pex is closer to the same size at 3/4" copper with the fittings, but wrestling 1" pex definitely would make things harder. I don't want to starve any baseboards that are downstream, but then I know the water doesn't flow that fast. It's 180 degree water and I believe it runs about 15psi, but I don't know the gpm of the pump at the moment, but can find out if that matters. I don't want to use push fittings so I'll sweat copper to pex adapters on.

 

[John Gayewski]

So I have hot water baseboard heat with three zones. The basement, bedrooms and main floor. The baseboard in the master bathroom is connected to the bedroom zone. We keep the bedrooms cooler for sleeping so I want to change that baseboard to the main floor zone otherwise the bathroom is freezing. It's all 3/4" copper piping. If I were to use oxygen barrier pex for changing that baseboard, what size can I use? I know 3/4" pex with crimp fittings are restricted a lot when compared to 3/4" copper and 1" pex is closer to the same size at 3/4" copper with the fittings, but wrestling 1" pex definitely would make things harder. I don't want to starve any baseboards that are downstream, but then I know the water doesn't flow that fast. It's 180 degree water and I believe it runs about 15psi, but I don't know the gpm of the pump at the moment, but can find out if that matters. I don't want to use push fittings so I'll sweat copper to pex adapters on.

You need to know how much heat you want before you can know pipe size.

Info you need

What piping setup your gonna use

How many btus on each baseboard zone (there's a lot more info needed but these will give you basic pipe size)


This is where it helps to make a schematic so you can diagram how many btus go to each section then you can start making pipe sizing measurements. The piping plan is really important also it can change pipe sizes based on how it's done. A primary secondary system will give you one main large loop (probably 1" or 1.25" depending on the load) then each secondary loop will get you smaller pipe.

Hydronic heating generally isn't very diy friendly to do correctly 100 percent. If you just wanna change pipe for pipe you'd upsize to be sure. If you want it correctly sized that's another more procedural animal.

 

[Sponsor]

 

[Taylorjm]

All the piping is 3/4” copper throughout. I don’t think there are any calculations that need to be done. I think you are overcomplicating things. I have a 4’ baseboard that I want to move from the bedroom zone to the main floor zone. There is only one pump and zone valves. So all I needed to know is if I can use 3/4” pex with crimp fittings. If not I’ll have to use 3/4” copper.

 

[Jeff H Young]

just run 3/4 pex and see how it performs . evedently there is something wrong with the system though or you wouldnt be experimenting. good chance a small change wont hurt

 

[Taylorjm]

just run 3/4 pex and see how it performs . evedently there is something wrong with the system though or you wouldnt be experimenting. good chance a small change wont hurt

There's nothing wrong with the system, just want the bathroom to be on the main floor zone instead of the bedroom so the bathroom is warmer since we keep the bedrooms cooler to sleep. Maybe I'll just run copper and use a pro press to make things easier. I've never used a pro press but people seem to like them.

 

[Jeff H Young]

Press is easy to work with pretty clean no burnt paint !

 

[Taylorjm]

Press is easy to work with pretty clean no burnt paint !

Yeah. A couple places are right by a bundle of electrical and insulation, which is why I was looking at pex. I’ve seen the less expensive hydraulic manual propress tools online. Maybe I’ll go that route.

 

[Taylorjm]

Press is easy to work with pretty clean no burnt paint !

I would use 1” pex in a heartbeat. I used a lot of it at my well and pressure tank, filters and softeners and it’s great, but I used the straight lengths, not the coiled. The oxygen barrier only comes in 5’ straight lengths instead of 10’ and not sure I want to put in a pex coupler to reach my baseboard. Seems cobbled if I do that but since it only runs about 15psi it would probable be fine. I really don’t want to wrestle with a 100’ coil of 1” pex my longest run is maybe 12’.

 

[John Gayewski]

Yes use copper.