Freezing Hydro Coils

BestMC

Is it possible for a DX R 410 coil to freeze a hydro coil downstream from it. We have had a hydro coil burst and explanation given was that the AC froze the heat coil. It seems strange to me but looking for other people's experience. Air handler is in a basement that is conditioned. There is no outside air connected to the ductwork. Outside air temperature at the time of incident was approx 40-45 degrees Fahrenheit. We did find that ac was on when it wasn't supposed to be.

Thanks

icesailor

Its always amazing the low temperatures that can be achieved when AC systems are low on gas/liquid.

I had photos of one that ran continuously for months, the compressor was a solid block of ice, and it froze the water pipes buried in the ground.

unclejohn

Yes it is possible. I repaired a hot water coil this fall that froze and leaked due to frozen A/C coil. On this unit the coils were about two inches apart. It is plain to see if the coil froze or just leaked. Frozen pipes split open and there is a "bulge " in the pipe. [Insert joke here ]

icesailor

Yes. And in my case, the soil around the water pipe froze, applying equal pressure around the copper water pipe, Any outward pressure by the frozen water/ice was canceled out by the frozen soil. Pipes may freeze in the ground, but they don't split. If the water stays fluid, it can crush the pipe from the outside, but the water inside can not split the pipe to the outside. Unless the pipe was surrounded by something like wood shavings.

clammy

As above stated i have seen a hydro coil freeze do to under charged outdoor unit .A cheap and easy fix for it is a manual reset freeze stat attach it to your suction line at your evap coil there where standard with unico equiptment .In most hydro coil i like to install a freez stat which closes and activates the heating circuit or goes to a alarm contact.Im also a fan of using check valves and 3 way by pass valves for hydo coil see way to much thermal migration when boiler is ran for domestic and there where no chk valves or chk installed on the circ pumps or even with zone valve systems .Its amazing that you can get thermal migration in a single pipe thats why i usually use check valves and freeze stats on all hydro coils it should be required also a hi temp discharge if your hydro coil is on the return side of yourr blower alot of blower motors don t perform to well with higher ambient if your running 180 water to that coil you might exceed manafacture max ambient ,Peace and good luck clammy