I'm sure this is not posted in the correct spot so if it gets moved could someone PM me and let me know.
I'm running a natural gas boiler and I have infloor heat(stapled pex to heat transfer plates in joists) on the first floor and second floor is cast iron radiators. I have them set up on two different zones. When the first floor (infloor heat) calls for heat the pex makes expansion noises for about 10 minutes until all the pipes have expanded and adjusted to the hotter water coming in. It's pretty loud and annoying.
Does anyone have thoughts on how to solve this problem?
As of right now i'm thinking of turning the infloor heat to circulate heat 24/7 and run it through a mixing valve. and then have the cast iron be on demand from the thermostat. Anyone else have a different thought or suggestion?
When i did the install, I placed the pipes at approximately 8in on center. I then stapled up the heat transfer plates that like the directions said. Next i placed the heat reflecting foil insulation about 1-2inches below the pipe to create an air gap. I thought i left plenty of room for expansion. I followed the directions. The majority of the noise is found under the heat transfer plates. However the noise is found in other locations. I've been reading up on the topic and the majority of the problems seem to be fixed by running the circulating pump 24/7 and keeping the temp between 90 and 120 degrees.
Sorry no pictures as i'm hoping that i don't have to pull down all the insulation.
there is a alternate handing method and that is pex stand off clamps that keep the per 1/2 inch below the floor. available at pex supply. you screw to floor above and just push the pex in and it lock with that one motion. Maufacturer though recomends 1 per 2-3 ft. I HAVE read alot about the issues with the transfer plates that many people with a lot of radiant heat experience recommend against them . I have also heard of adding talcum powder to the plates prior to install, dont know though it it works. like is on armaflex insulation . Pex expands far more than copper as you /mehave found out.
I have a couple of small loops i have just installed with the stand off clamps and noise is almost non existent. pexsupply has the stand off clips . All loopsrunning efm 520 produced 180 degree water , well almost 180 its 180 at boiler and its traveling from another building 130 ft away.
I believe in the 'stand-off' clamping method also. But I also believe in sleeving heat lines of any kind. It is no big deal at the time of install, and saves all the aggravation later. Nothing better than being in a home that has thermal expansion squeaks, especially when you KNOW who did the install. The follow-up call asking if it can be fixed is no fun to answer either.
so in the "stand-off"method do you suggest that there is No heat transfer plates? In the stand off method i'm assuming you use the heat/reflective insulation. But how far below the pipe do you install it? in your projects are you in stalling R19 insulation below the heat/reflective insulation?
I don't think you should need to run your water 24/7 although if you did do that then you need to mix it down closer to room desired temp. So if you are wanting your heated area to be at 70 deg you'll need to run that loop at 70 or very close to that I suspect. Remember that zone/area will be "heating" 100% of the time if you go that route.
The cast iron on the second floor is on it's own loop. It has it's own circulator pump. The in floor heat is on it's own run as well. So there are two loops. My next approach is to set it up with a low temp on first floor. Hopefully a 100 degree temp will help out.
If you lower the water temp in the underfloor loops to 100 you almost certainly wont get any heat out of it. When pex is in concrete you can do that because the pipe is all encased and therefore there is greater heat transfer. You might be able to get away with 140 degrees not sure.Im thinking you should remove the plates and staple up the pipe , it wont make any noise except where a 1/2 inch pipe goes through a 7/16 hole!
Okay so here is my thoughts. I've lowered the temp by adjusting the mixing valve. I still have expansion noise. I'm not sure which method would be best. Please give me feed back on your thoughts and experiences.
Now that the floor has pex and transfer plates stapled to the subfloor i have two options.
option 1 Run circulator 24/7 and let the low temp. radiant with the heat transfer plates. Using a mixing valve this will keep the water at a much lower temp and because the ciruclator is running 24/7 will remove the expansion/noise problem. For the 15.00 per month that would be fine by me because i think i'm saving that by running at a lower temp.
option 2 Remove the heat transfer plates. Staple up the pex and then reinstall the foil backed/reflection. This will require a higher temp to run at but will not require a 24/7 circulator pump.