Expansion noises from runtal baseboard (Ray L)

Ray Landry_3

No ideas?

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Ray Landry_3

Went back on a system we installed over the summer today. Master bedroom suite added to an old home outside of boston. Existing home is mostly wall convectors with some runtal bb. We installed a seperate 3/4 fostapex zone for 6 pieces of 2 tiered runtal baseboard. Piping is in a 3' crawlspace very well insulated.

The problem is that a 10' section of runtal baseboard is making LOUD expansion noises very similar to a back pitched steam rad. I checked all the obvious stuff (I think!) larger than needed holes for the riser pipes, no pipes touching wood in the crawlspace, plenty of room for the pex to expand.

Using my infared thermometer I determined that I was only getting an 8 degree delta tee from the first baseboard to the last (Series loop system, which I don't entirely agree with but according to runtal should work) so I went down to the buderus pump station and changed the grundfoss 1558 circ to speed one, opened the pressure differential bypass more, and increased my delta T to 20 degrees. This had no effect on the noise at all. Runtal says it's caused by velocity noise but the way I figure it I'm moving about 1 1/2 gallons a minute through the loop which in my opinion shouldn't be excessive. I also made sure the wall brackets where mounted straight and the baseboard could move freely (per runtal) It's just very odd to me that this is only happening in this one baseboard. It is the second baseboard in the loop, and it occurs through the entire cycle even once the bb has heated up substantially.

I've got an outdoor reset control on this job so ultra hot water temps aren't an issue. I'm thinking of installing an expansion joint in the crawlspace, or maybe converting the baseboards to a venturi system. Any ideas guys?

Brad White_9

Sorry, Ray

All the things you looked at seem to be what I would think of and then some. FostaPex, hangers, reset, low temperatures given the weather we have been having, no binding...

Is the noise in a particular part of the Runtal? Is it truly expansion? Could it be an internal baffle plugged with some paint chips or a piece of plug?

Just fishing here I know.

Where is the job? E-mail me off line if you like. Maybe I can come by next week and take a look if it is not too far. I am off next week.

Brad