Connecting Radiator to Copper Supply/Return Lines - What adapters?

HandyFS

I'm replacing an old cast iron radiator that was damaged. The supply/return lines are both 1/2 Copper stubbed up from the ground. What is the best method to adapt from the 1/2" copper to the 1/2 NPT female valve on the supply side?

Supply Side:
Is a straight threaded male copper connector directly into a bronze radiator valve ideal? Does it make sense to use a brass nipple instead in-between? Is there a different combination of connectors that I should consider instead to go from the 1/2" copper supply into the radiator valve?

Return Side:
On the return side, I am planning on using a 1/2"Copper Union Fitting with Sweat directly to the copper. This will act as a union in case the radiator ever needs to be removed.

I was hoping a 1/2 NPT Male threaded to 1/2 Female sweat adapter existed, but I can't seem to find one anywhere. I know these are common when going from copper to pex, but I couldn't find anything that had NPT threads.

All tips on the supply side appreciated.

hot_rod

A common 1/2" copper to male adapter is male NPT, by copper hub.
Both male and female copper adapters are also available as street versions. meaning the copper sweat end goes into a fitting instead of over the tube.

You can also find ell versions of copper to male adapters. They are rare but street copper ells X npt male or female are also out there.

The bottom left female fitting kinda looks like a street version in your pic.

I think copper press fittings are also available in standard and street versions, for NPT transitions.
I'd look for the least amount of threaded connection solution.

HandyFS

hot_rod said:

A common 1/2" copper to male adapter is male NPT, by copper hub.
Both male and female copper adapters are also available as street versions. meaning the copper sweat end goes into a fitting instead of over the tube.

You can also find ell versions of copper to male adapters. They are rare but street copper ells X npt male or female are also out there.

The bottom left female fitting kinda looks like a street version in your pic.

I think copper press fittings are also available in standard and street versions, for NPT transitions.
I'd look for the least amount of threaded connection solution.

Thanks Hotrod!
So the copper threads are worthy enough to thread into the bronze radiator valve reliably? I was thinking brass is more durable than copper, so try to get over to brass for the threads.

So in that case of less threads, should I just go straight into the brass valve with a copper NPT Male?

Or is it better to use a female threaded NPT connector and use a nipple in-between the copper and the brass valve?

Or, can you share a photo so I follow what I'm looking for?

If the brass female NPT threads are worthy, I'll go direct into the valve with this:

dko

Search radiator union elbow
https://www.zoro.com/legend-valve-12-s-438-sweat-union-elbow-110-165/i/G3042386
https://www.supplyhouse.com/Bluefin-RVES075-3-4-CXC-x-Male-Union-Brass-Radiator-Union-Elbow
https://www.supplyhouse.com/Bluefin-RVE050-1-2-FIP-x-Male-Union-Radiator-Union-Elbow (put a male adapter)

1/2" isn't too common, mostly ran in 3/4". you'll be able to find the 1/2" in sweat online

Just put a male adapter, don't need brass nipple.

EdTheHeaterMan

PVC for electric conduit, like the DIY previous owner did for my water service, should be fine

NOT

HandyFS

EdTheHeaterMan said:

PVC for electric conduit, like the DIY previous owner did for my water service, should be fine

NOT

I'm just here to learn and do. I've learned far more than I would like about boilers, radiators, and everything else hot water heat related, and I thank you all for the knowledge you've all shared as I reference lots of your old posts and a lot of the regulars here that have such great knowledge.

This is getting done either way, I'm just hoping to get it right the first time.

Any tips appreciated.

HandyFS

dko said:

Search radiator union elbow
https://www.zoro.com/legend-valve-12-s-438-sweat-union-elbow-110-165/i/G3042386
https://www.supplyhouse.com/Bluefin-RVES075-3-4-CXC-x-Male-Union-Brass-Radiator-Union-Elbow
https://www.supplyhouse.com/Bluefin-RVE050-1-2-FIP-x-Male-Union-Radiator-Union-Elbow (put a male adapter)

1/2" isn't too common, mostly ran in 3/4". you'll be able to find the 1/2" in sweat online

Just put a male adapter, don't need brass nipple.

The replacement radiator is shorter than the old radiator by a little bit, so I can't use the 90 degree union since I need to run horizontally first. I searched high and low for a radiator valve and union that were horizontal, not 90 and seem almost impossible to find.

On the return side, I'm using a union like this:
https://www.amazon.com/gp/product/B016Y8OIBI/

On the supply side, I didn't want to use a radiator valve that has a union, and then another union to connect to the copper. So I'm trying to minimize the connections on the supply side.

So the male copper threaded directly into the bronze valve is a reliable connection? If so, the least amount of non-sweated connections sounds like a win.

dko

Couldn't you use it for one side if you moved the radiator over? If centering for aesthetics I can understand.

The male adapter you are looking for it https://www.amazon.com/Everflow-FCMA0012-5-Adapter-Fitting-Connections/dp/B016Y8MS0G
It will be labeled as FTG (fitting) x Male Adapter. or male sweat

If you have 1/2" connections on the rad, assuming european style?
They usually have valve sets straight/angle for your brand like
https://www.supplyhouse.com/Runtal-VALVE-ST-SET-Standard-Straight-Shut-Off-Valve-Set-for-All-Models

HandyFS

dko said:

Couldn't you use it for one side if you moved the radiator over? If centering for aesthetics I can understand.

The male adapter you are looking for it https://www.amazon.com/Everflow-FCMA0012-5-Adapter-Fitting-Connections/dp/B07VLJPD3F/

It will be labeled as FTG (fitting) x Male Adapter.

If you have 1/2" connections on the rad, assuming european style?
They usually have valve sets straight/angle for your brand like
https://www.supplyhouse.com/Runtal-VALVE-ST-SET-Standard-Straight-Shut-Off-Valve-Set-for-All-Models

This is very helpful, thank you!

That adapter I think is my best bet, I'm going to find that specific one if I can.

I could in theory off-set the radiator, but its in the living space in a cut out underneath a window, so I'm trying to keep it centered if possible. This is an old standard USA cast iron radiator, for whatever reason some of the supplies are 1/2 Copper to certain locations in the house. Seem to work fine so I'm going to run with them as long as they function.

EdTheHeaterMan

I was only kidding and then got called away. Sorry for the sarcasm without the normal "Real info" I usually add. I hit send before I should have.

But to get to the nitty gritty...

You want it to look nice so the standard radiator fittings are in order for the panel you show. They are designed to keep the union to the radiator looking neat and professional. They come in chrome and brass. Depending on the use of thermostatic radiator valves or just manual valves you would select a return bend to match the supply valve.

https://www.supplyhouse.com/Bluefin-RVHW075-3-4-FIP-x-Male-Union-Hot-Water-Angle-Radiator-Valve?_br_psugg_q=3/4+radiator+valve

https://www.supplyhouse.com/Bluefin-RVE075-3-4-FIP-x-Male-Union-Radiator-Union-Elbow
These are economical. depending on your taste you can get much more elaborate radiator hardware.

From those threaded fittings That face to the floor (or the wall) I would use as few fittings as possible to get back to the boiler or manifold or main feeds. The idea you have of using a short brass nipple then a female adaptor to copper is just adding more locations to leak.

I might suggest that you move directly to PEX piping from the valve and return elbow. If there is a few inches of PEX visible between the floor (or wall) and the radiator valve you can cover it with a chrome cover available from amazon.com. https://www.amazon.com/dp/B0039823UU?ref=ppx_yo2ov_dt_b_product_details&th=1 These are actually plastic covers that look like chrome and will fit over ½” to 1” copper or PEX to make the “dirty work” look awesome. I have used them many times. Just wrap around the pipe after the system is installed.

EdTheHeaterMan

This is a double post. @Erin Holohan Haskell can fix this and place it on the main wall since it is not a steam radiator.

As far as getting a strait valve to copper, Would this work? https://www.supplyhouse.com/Webstone-H-50422W-1-2-Sweat-x-FNPT-Union-Full-Port-Ball-Valve-Lead-Free

You could remove the handle and go to a local machine shop and have a round handle fabricated to look good on that radiator.

dko

https://www.zoro.com/legend-valve-12-s-425-circulator-valve-110-217/i/G3043506/

Erin Holohan Haskell

EdTheHeaterMan said:

This is a double post. @Erin Holohan Haskell can fix this and place it on the main wall since it is not a steam radiator.

Thanks @EdTheHeaterMan!

@HandyFS, I've merged your duplicate posts into one here to prevent confusion.

HandyFS

EdTheHeaterMan said:

This is a double post. @Erin Holohan Haskell can fix this and place it on the main wall since it is not a steam radiator.

As far as getting a strait valve to copper, Would this work? https://www.supplyhouse.com/Webstone-H-50422W-1-2-Sweat-x-FNPT-Union-Full-Port-Ball-Valve-Lead-Free

You could remove the handle and go to a local machine shop and have a round handle fabricated to look good on that radiator.

Thanks Ed! Sorry about the double post, I thought it submitted but then it refreshed and let me choose a category so that was my fault.

That's an idea, this setup probably would be fine with no handle on it if I had to.

dko said:

https://www.zoro.com/legend-valve-12-s-425-circulator-valve-110-217/i/G3043506/

Wow, this is literally what I've been hoping to find for so long. Unfortunately it seems nobody could get it to me fast enough since my plumber already has me scheduled.

Is it safe to say this 1/2" Copper Female adapter threaded into the radiator valve, and the other end sweated to the copper will suffice?
https://www.supplyhouse.com/Elkhart-30310-ELKHART-1-2-Copper-x-Male-Adapter

HandyFS

EdTheHeaterMan said:

I was only kidding and then got called away. Sorry for the sarcasm without the normal "Real info" I usually add. I hit send before I should have.

But to get to the nitty gritty...

You want it to look nice so the standard radiator fittings are in order for the panel you show. They are designed to keep the union to the radiator looking neat and professional. They come in chrome and brass. Depending on the use of thermostatic radiator valves or just manual valves you would select a return bend to match the supply valve.

https://www.supplyhouse.com/Bluefin-RVHW075-3-4-FIP-x-Male-Union-Hot-Water-Angle-Radiator-Valve?_br_psugg_q=3/4+radiator+valve

https://www.supplyhouse.com/Bluefin-RVE075-3-4-FIP-x-Male-Union-Radiator-Union-Elbow
These are economical. depending on your taste you can get much more elaborate radiator hardware.

From those threaded fittings That face to the floor (or the wall) I would use as few fittings as possible to get back to the boiler or manifold or main feeds. The idea you have of using a short brass nipple then a female adaptor to copper is just adding more locations to leak.

I might suggest that you move directly to PEX piping from the valve and return elbow. If there is a few inches of PEX visible between the floor (or wall) and the radiator valve you can cover it with a chrome cover available from amazon.com. https://www.amazon.com/dp/B0039823UU?ref=ppx_yo2ov_dt_b_product_details&th=1 These are actually plastic covers that look like chrome and will fit over ½” to 1” copper or PEX to make the “dirty work” look awesome. I have used them many times. Just wrap around the pipe after the system is installed.

Hey Ed,
Thanks for this post, I missed it earlier in the merging of threads. VERY Helpful, and I appreciate you taking the time to share it all.

For this particular radiator, it is slightly shorter than the old one was. The space is unique under a window and I could not find anything remotely close to the same size, so I settled on a radiator that is just a bit shorter left to right. So the angled radiator vales won't work in this case. Those angled valves you suggested to me worked out extremely well in some of the other radiators I replaced though.

I've been through a bunch with this house and the radiators, so I did some replacement on the 1st floor with pex and with those exact radiator covers. All in all it worked out decent, outside of the spots where I used the stainless pex clamp to hold the pex together.

In my case, it seems the horizontal/straight steam radiator is probably the best bet:
https://www.supplyhouse.com/Matco-Norca-BSGV-0500-1-2-FIP-x-Male-Union-Steam-Radiator-Gate-Valve

Sorry for being such a DIY newbie to all of this. I've figured out nearly all of the other radiators in the house and have them working great. I saved the 2 hardest ones for last, and this is the hardest of them all.

Could I use that copper female adapter to thread directly into this steam valve? Or is that not ideal/practical? I could then get the copper reworked to perfectly align directly into this steam valve and it would then only have that one connection outside of the radiator valve union on the radiator side. Is this ideal? I've seen these copper threaded connectors threaded into brass shower valve assemblies, so I'm assuming it would be ok to use in this scenario?

mattmia2

Is the new radiator steel or cast iron? If it is steel it will heat and cool faster than the cast iron radiators and you may have trouble balancing it with the rest of the system.

hot_rod

This ell takes one sweat connection out of the assembly and tightens up the dimension from radiator to hole in the floor. 1/2" sizes only from Nibco.

With a brass wire brush in a drill or angle grinders you can buff the brass valve and fitting up nicely. Spray enamel it to keep it shiny and easy to clean.

mattmia2

Copper adapters in to brass are fine. They are fine even in to steel on a closed hot water heating system.

HandyFS

mattmia2 said:

Is the new radiator steel or cast iron? If it is steel it will heat and cool faster than the cast iron radiators and you may have trouble balancing it with the rest of the system.

Copper adapters in to brass are fine. They are fine even in to steel on a closed hot water heating system.

Great point to make on new steel vs old cast iron, thanks for this. I replaced with an old school cast iron radiator I picked up used since this is a main radiator in the room and I wanted to be sure it functioned as close to how it did before. Pressure tested, repainted, and ready for action. I had to replace a bunch in this house due to freeze damage.

Happy to hear the copper adapter directly to the valve will suffice.

hot_rod said:

This ell takes one sweat connection out of the assembly and tightens up the dimension from radiator to hole in the floor. 1/2" sizes only from Nibco.

With a brass wire brush in a drill or angle grinders you can buff the brass valve and fitting up nicely. Spray enamel it to keep it shiny and easy to clean.

The brass elbow would be nice if the rest of the system looked good, but its a pretty basic setup so I'll probably come up with copper and then just cover it the best I can. It used to be painted to match the radiator and it seemed to hold the color well, so that's an option to make it all blend in. Also on this one, unfortunately the replacement radiator is a bit short so I have to run horizontally a bit before it reaches the radiator/valve, so we are mainly going for function vs fashion on this one


THANKS AGAIN EVERYONE!
Copper to brass adapter is how I'm going to go this round I think since I can get this stuff quickly, and get this radiator back in use soon. This configuration it is, unless there is something else I can whip up in the next few days before the plumber comes to help me sweat it all together.