Pipe for hot water heat

[aczlan]

So, a house has hot water heat and galvanized/copper pipe. There are several radiators that will need to be replaced and some others that could stand a to be worked on.
What is recommended for line to run water to and from the radiators?
I have seen PEX listed for heating runs in radiant floors, but is it commonly used to supply radiators and/or radiant panels?

Thanks

Aaron Z

 

[schmism]

steam radiators or hot water?

It was my understanding that due to the flow rate required (for hot water) that supply lines to them were generally much larger than standard water supply lines for the rest of the standard plumbing.

ie were 1/2" lines are normal for most fixtures, my parents radiators are plumbed with 1" until the rad when they nec down to 3/4"

Dont think i would consider useing 1" pex for such and application. I would stick to copper/galv (something rigid) and remember to include insulation on the pipes.

 

[aczlan]

steam radiators or hot water?

Hot water.

Aaron Z

 

[AKwelder]

In alaska we are running non commercial lines in pex under these conditions:

1) Boiler temp, the boiler needs to run under 180
2) flow, the line can not be a constant flow
3) we do not run through floors with pex, we switch to copper

This has been happening for over 10 years and i don't know of any failure that were not related to abuse or improper instlation

 

[AKwelder]

your line size is due to your BTU's carried. If i remember correct it turns out to be 10,000 BTU per hour for each gallon flowed at a 10 degree temp change

or goto heatinghelp.com

 

[Kays Supply]

AKwelder, what are the problems with constant flow and PEX? I am new to installing PEX. I want to learn all I cam before I make mistakes.

 

[DIRTROAD]

I recently removed five old radiators from a house. Each one is designed different, but they all have one thing in common. They each have a device to slow the water flow down either before or after the radiator. I can't remember which side of the radiator it was on. All of the plumbing was galvanized. I still have all of it if you need any pieces.

 

[2manyrocks]

That brings back memories. Used to live in a house that had radiators like that. I can remember the thumping and the other noises the system used to make, but it sure heated the house. I suppose they sized the radiators to the heat load in the different rooms. The supply pipes as I recall where about 1 1/2 inch galvanized pipe. The labor costs to install the same system today would be substantial.

 

[AKwelder]

The way we use PEX is very close to it's max temp limit, the rating is not for constant flow this close to its max temp.

Some of the old radiators were installed in buildings that started with steam heat and different pipe sizes. The old coal fired steam boilers were HUGE and the pipes that were used were also huge. Now we use hot water systems that are sized closer to the actual heat need.

 

[schmism]

I recently removed five old radiators from a house.

with only one pipe in... those are steam radiators. hot water always have 2 pipes one on either side.

They each have a device to slow the water flow down either before or after the radiator.

those would be the steam regulators to regulate how much steam is let into THAT radiator. again water radiators have no flow restrictors other than water valves that are commonly found on the input side. and the valves generally arnt used to control flow, simply just shutoffs.

 

[DIRTROAD]

These have a pipe on each side. An entry and exit. One is up high at the top and the other is down at the bottom. The little device has a knob or dial that can be turned to adjust the flow.

 

[2manyrocks]

These would make good antiques. I bet you don't see many of these radiators around any more. The house I lived in that had them was built probably around 1910, and I think the radiators probably dated from that period. The boiler itself had been replaced probably several times, but the pipes and the radiators were probably original to the building.