changing a radiator valve to a TRV

R. Kalia_8

OK, this is a stupid amateur question, but I am an amateur. I should be able to change a right-angle radiator valve to a TRV, though.

Here's what I don't understand. The connection to the radiator is a union, but the bottom of the valve where it goes on the riser pipe is just a threaded female. So I have to screw the valve onto the riser before connecting it to the radiator.

But won't the radiator get in the way, I mean, won't the union hit the radiator every time I turn the valve around to tighten it on the riser? And at the end I won't be able to insert the valve into the radiator? Actually, the way I am visualizing it, I won't even be able to get the old valve off, never mind put a new valve on.

Is the riser pipe kind of floppy so I can push it away from the radiator? I don't see how, because the hole in the floor isn't large enough.

Mike T., Swampeast MO

If everything is incredibly tight you slightly loosen the left-hand connection (using two wrenches of course) while another person pulls that end of the rad. The geometry of TRVs is identical to the old valves.

Steve D_9

Can you undo both unions on the radiator and slide it away? You are also going to need clearance to remove the stub in the TRV end of the radiator.

Steve

Mike T., Swampeast MO

That's the usual way when the piping has a bit of "give".

R. Kalia_8

Ah, OK, I didn't think of disconnecting the other side of the radiator. That should give me a little more slack. Thanks to everyone for the help!

R. Kalia_8

ANOTHER QUESTION

>The geometry of TRVs is identical to the old valves.

Actually the geometry is not exactly identical, but this is not related to the original question.

The Danfoss horizontal-angle valves have a much shorter vertical section than the valves currently on the radiator (I sketched the current manual valve in red in the picture below).

Do the vertical riser pipes usually have enough "give" to be pulled up maybe 2", or will I need to add a section of cast-iron pipe? I am asking because I want to be ready with all necessary pieces pre-made and do the work quickly before the house gets too cold in this weather.

Mike T., Swampeast MO

Interesting. I've replaced hand valves from at least three different manufacturers with TRVs and all were perfect fits.

I know they look different but measure from the supply connection to the center of the spud and see if it doesn't match.

Very doubtful you'll find 2" of vertical play.

Steve D._4

Can you send a picture with a tape measure scale next to the valve? You need to measure from the centerline of the spud to the bottom of the hexagonal part of the lower valve. The vertical valves do look much taller but you are only concerned with the lower section of the old valve.

Steve

R. Kalia_4

so I'm slow...

They're exactly the same. Thanks for being patient with me.

R. Kalia_4

so I'm slow...

They're exactly the same, although they do look different. Sorry about that.

Mike Cascio

What type of heating system is this?

Is it one pipe steam, two pipe steam, or is it Hot water?

Michael J. Cascio

will smith_4

Installing thermorad valves

Jim- If you don't already have one, you might want to lay hands on a spud wrench-they make removing the male part of the union A LOT easier. You might be tempted to use a valve assembly with the adjustment knob designed on the top, as oppsed to the side shot you've shown us(maybe tight space)If you need to go that route, you'll need to get a different type of power head-one with a cap tube type sensing element. When the power head sits atop the valve (compared to the horizontal position) it won't give the same level of control. Good Luck!

R. Kalia_8

Thanks! I will install the valve type shown in the picture, so that the head is horizontal. The remote heads are too much trouble. I have the space for the horizontal heads.

I just ordered the parts from PatriotSupply.com...probably more expensive than our local hydronics supply house, but they won't sell to me (and from my posts above you can see why!)

R. Kalia_8

Hot water, sorry, I should have said that up front.