We had our basement "refinished" with a retrofit radiant floor heat system using a propane combi boiler; one zone. This is a small 2-BRM 1500 sq ft ranch home. Basement walls/floors/ceiling are finished except for where mechanicals are, It is heated by 2 infra-red electric fireplaces when we occasionally use the basement. The mechanicals section behind closed doors is 200 sf with NO drop ceiling; but has the pex/plates/reflec. foil. About half the 1000 sf basement has a drop ceiling. The 1/2" red pex w/O2 barrier tubing now has areas of heat transfer plates, as we put them in. Then the reflective foam insulation is up against the pex/plates. I have checked that the pex is not rubbing against the wood, but when the heat is called for (max 140) for a while when heat comes on there is a lot of ticking and almost sounds like dripping of water on metal. It is annoying and I can isolate the sound by quickly running downstairs and listening and watching, noting typical expansion/contraction of pex within the plates, but the tubes are snug in the plates, so what is making the noises and how can I suppress them? I tried putting some rolls of sound deadening material, - 1" eggcrate with black backing as used to soundproof a room - did help a bit but not enough.. Again, it is only when the system calls for heat. There is no air in the system, the manifolds are all fine. The pex is not all entirely visible along the portions of the ceiling and bulkhead that was closed in with sheetrock when the basement was finished, but we can shine a light along and see that the pex is in contact where it should be. The contractor did not use plates. We installed them where we could get to them because there were so many cold spots in the floors above. He was rather sloppy in getting some of the pex against the floor in places, but we feel we corrected that. Do you think it would help to add more of the noise barrier between the plates and reflec foam foil where we hear the noise? Thank u.