Pex-Al-Pex to replace old hot water heating pipes in NYC


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Old 01-10-10, 08:56 PM
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Pex-Al-Pex to replace old hot water heating pipes in NYC

Hi Everyone,

I recently bought a 1930's house. The boiler is fairly new, hot water system. There are 2 runs of 2 1/2 in black pipe that feed pairs of 1 1/4 black pipe to each radiator (feed & return). the 2 1/2" runs in the middle of the basement and has T's for each of the radiator runs. most of the 1 1/4 runs are in the walls, so they cant easily be replaced. I wanted to rip out the old 2 1/2" and run home runs of Pex-Al-Pex to a set of manifolds. The existing system has only 1 circuit/zone, but would love to do 2 (1 for 1st fl & 1 for 2nd - bedrooms). I have a few questions that I hope the experts here can help me with
1 - can I even use Pex-Al-Pex in NYC (queens) for heating? I know it's not legal for potable water,but was told by 1 plumber that it IS allowed for heating. Does anyone know for sure?
2 - what type of fitting do u recommend to make the transition from the 1 1/4 black to Pex?
3 - what size Pex, 1/2 or 3/4? each radiator will be a home run to the manifolds.
4 - for a 2 zone system do I need 2 manifolds (feed & return) or 4?
5 - there are 2 upstairs radiators that I need to re-route in the walls of the kitchen - walls & ceilings of kitchen are down to the studs. should I run the Pex into the radiators or to the 1 1/4 nipple? I'm concerned with leaving any connections buried in the wall. What type of connector should I use to go into the old style radiator from Pex?

I was thinking of running the home runs myself and having a plumber, drain the system & do the connections to the boiler, radiators & wire up any controls. have to save money somehow any advice, warnings to keep in mind?

thank you very much for your expert guidance and advice! learned alot from reading these forums.

Thanks,

Nick
 
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Old 01-11-10, 04:56 AM
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1. dunno.
2. Try Watts, Caleffi, Uponor/Wirsbo.
3. It depends on the load you are serving, the design flow rate, head loss of piping.
4. Depends on what kind of manifold.
5. dunno.

DIY all you want. Just be advised that the good pros will be very reluctant to take responsibility for a DIY job. Once they touch it, they own it. They will have to trust that you did everything right. Don't be offended if they make you sign off on a fairly comprehensive waiver.
 
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Old 01-11-10, 08:18 AM
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thanks

Hi Xiphias, thank you for your reply.

understand the potential concern, but the home runs would be in the basement and visible, I'm not making any connections, just saving the plumber some time.

The house is 1900 sq ft and there are 4 radiators on the 1st fl and 4 on the 2nd, so nothing too large or fancy. I wasnt sure if each zone needs it's own maidfolds or if all the home runs can terminate into 2 (one for feed & one for return) and then use zone valves (or whatever other option) to control the flow, with 2 thermostats.

in terms of the connections to the existing black pipe, is this ok to do? any potential issues to be aware of? what do folks usually do in these circumstances?

I could always have the plumber run copper lines, but it will cost a small fortune. looking for flexible, lower cost alternatives

BTW, are u greek? curious because of your screen name xiphias

Thanks again!

/Nick
 
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Old 08-28-10, 06:09 PM
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Did you ever replace the pipes

I am in a similar situation, converted a old gravity system to natural gas boiler. I still have the thick 2 1/2-3"" inch piples that I would like to replace. I have two questions

since I no longer have gravity will there be an issue to go from a 3" pipe to a 1 1/2 copper pipe? - I would think this would be more efficient and cost effective option.

second I have two large pipes(supply, return) with a pair of pipes running to each radiator my father seems to think we can reroute pipes to get rid of supply and more or less daisy chain all the pipes/radiators to feed off one supply pipe. is this possible..
 
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Old 08-30-10, 08:23 PM
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Originally Posted by nickt
Hi Xiphias, thank you for your reply.

understand the potential concern, but the home runs would be in the basement and visible, I'm not making any connections, just saving the plumber some time.

The house is 1900 sq ft and there are 4 radiators on the 1st fl and 4 on the 2nd, so nothing too large or fancy. I wasnt sure if each zone needs it's own maidfolds or if all the home runs can terminate into 2 (one for feed & one for return) and then use zone valves (or whatever other option) to control the flow, with 2 thermostats.

in terms of the connections to the existing black pipe, is this ok to do? any potential issues to be aware of? what do folks usually do in these circumstances?

I could always have the plumber run copper lines, but it will cost a small fortune. looking for flexible, lower cost alternatives

BTW, are u greek? curious because of your screen name xiphias

Thanks again!

/Nick
How many BTU is the boiler.
Sounds like a small house, I doubt you would have an issues running a 3/4" supply out to all the 2nd floor risers, and bringing the returns back with a second 3/4" pex line. Do reverse return if you want to get real fancy.
Do the same for the main floor.

Use zone valves for each supply line, and make sure the pump. and air seperator are in the supply (hot side) of the boiler. Put a couple GLOBE valves on the return, and maybe 2 temperature guages to balance the zones.

You should be good to go. Don't forget about boiler protection if it isn't already there and outdoor reset.
 
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Old 08-30-10, 08:28 PM
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Originally Posted by npanarella
I am in a similar situation, converted a old gravity system to natural gas boiler. I still have the thick 2 1/2-3"" inch piples that I would like to replace. I have two questions

since I no longer have gravity will there be an issue to go from a 3" pipe to a 1 1/2 copper pipe? - I would think this would be more efficient and cost effective option.

second I have two large pipes(supply, return) with a pair of pipes running to each radiator my father seems to think we can reroute pipes to get rid of supply and more or less daisy chain all the pipes/radiators to feed off one supply pipe. is this possible..
Hard to say with out knowing quite a few things.
BTU of the boiler, and the capacity of the rads.
Type of rads (most likely cast iron)
number of rads.

Most often the main floor can be seperated from the 2nd / 3rd floor risers.

I doubt you would need 1 1/2" copper, but I don't know the load
 
 

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