Installation of Hot Water Heating Pex Pipes and Runtal Radiators

KenH

Does anyone have any experience converting a steam system to a hot water system using Pex piping and runtal wall panel radiators?

SWEI

Converting?

Sounds more like replacing.    We've done quite a bit over the years.  I wouldn't actually  recommend it unless the steam system uses low mass convectors or there are other extenuating circumstances.

Jamie Hall

Let's see here...

heating medium was steam, to be hot water



piping was threaded iron, to be pex



radiators, at a guess, were cast iron, to be runtal wall panels.



That's not a conversion, that's a complete tear out and rebuild.



No comment....

Scott_Mountain_View_CA

"No comment"?

Let's not get hung up on how the OP worded his question. He's asking for help installing a Pex and Runtal panel system. I too am considering a Pex and Runtal panel combination and will be watching this thread for info, particularly any discussion relative to pipe sizing.

KenH

Clarification

Sorry, i guess it is part new installation and part conversion.  I was told by a local plumber my steam boilers is able to be converted to a hot water boiler, and being that it is only 10 years old that is probably the most cost effective option on that end.  But I will worry about the boiler at a later date. 

As for the radiators and piping, My steam system works good, but as renovate the house and insulate and add new windows/door some rooms are becoming too hot.  I believe that by the time i am done with everything the system itself may be too overpowering for a well insulated house.  In addition, i would like to finish off the basement and it is imperative that i remove the steam pipes hanging from the ceiling to get proper head clearance.  Finally most of the system is almost 100 years old, and i can see in the future some of the pipes giving me problems.  So why i am renovating and have some walls open, now is the time to run the pex piping.

Basically i wanted to get a fee about the runtal system and if anyone has any pros or cons about the radiators.  Also I will be running the heat pipes in the exterior walls and wanted some guidance doing this.  I ordered one radiator last week, just to get a feel for what i am up against.  It doenst look too dificult, there are just some key questions that i have.

I am a carpenter so i have been around construction my whole life.  i feel that i will be able to hook everything and make the home runs to the basement.  When all that is done i will have a plumber make the conversion and connections.  

KenH

@scott_mountain

Pipe sizing is a question i had as well.  The runtals use 1/2 NPT inlet and outlet pipes.  So the guy at the supply house quoted me 1/2" pex oxy barrier pipe.  I always thought that heat was in 3/4 piping.  Not sure if this is correct, but maybe the runtals are more efficient so they require a smaller diameter pipe.

SWEI

Radiator pipes

rarely carry more than 1 GPM.  In a home run system, that is all they have to carry.



In a series baseboard system, the pipes have to carry several rooms' worth of flow.

bennyboy

I have 3/4 inch non oxygen barrier PEX feeding 120-170 F water to 60 feet of these Runtal radiators at 1/2 to 1 gallon per minute.
Yes I went to 1/2 brass at the ends of radiators.
I feed them across 3 zones and in series or used mono flow tees when I couldn't in the parallel circuits.
I have a modulating boiler that is supplying the heated water.

I am very happy with the looks and heat being delivered.

I can share installation tips learned and what not to do.
History... I removed all of my force hot air duct work and used a mixture of both pex in floor radiant and baseboard.

Paul Pollets

If your new to the trades, 1/2" barrier pex homeruns to each Runtal, terminating in a distribution manifold is the easiest way to convert. However, if you have 10 radiators, you'll have 20 pipe runs entering the mechanical room, you'll have to consider if the piping can fit. 1 -10port manifold would do the job. The boiler piping to the manifold would be 1". The Runtals should be fitted with thermostatic radiator valves (TRV's) on the supply. I'd change the boiler if budget allows, to a modulating condensing appliance.

SWEI

bennyboy said:

I have 3/4 inch non oxygen barrier PEX feeding 120-170 F water to 60 feet of these Runtal radiators

With that approach, you'd better plan on some chemical treatment. Use barrier tubing with steel or iron radiators.

hot_rod

If you use an H valve with adjustable bypass you can put 2, maybe 3 radiators on one loop, that would cut down on the number of runs.

A room by room load calc first, then determine operating temperature, then select radiators making sure 1/2 or 5/8 can supply that loop.

I agree the home run method to one or multiple manifolds is a great way to pipe them. You have unlimited adjustability and isolation if you need. With a manifold every radiator gets the same supply temperature.

One mistake commonly made is not properly fastening the pex runs to prevent noise.

http://www.caleffi.com/sites/default/files/file/01036_na.pdf

Good guidelines for manifold piping here.

http://www.caleffi.com/sites/default/files/coll_attach_file/idronics_4.pdf

jumper

Paul Pollets said:

If your new to the trades, 1/2" barrier pex homeruns to each Runtal, terminating in a distribution manifold is the easiest way to convert. However, if you have 10 radiators, you'll have 20 pipe runs entering the mechanical room, you'll have to consider if the piping can fit. 1 -10port manifold would do the job. The boiler piping to the manifold would be 1". The Runtals should be fitted with thermostatic radiator valves (TRV's) on the supply. I'd change the boiler if budget allows, to a modulating condensing appliance.

How about individual runs for supply but tee into common returns? More work but less spaghetti in boiler room.