radiant heat, boilers and heat exchangers
I have a 6 zone radiant heat system with a boiler attached.
4 zones are for the basement, and 2 are for the garage.
(The main floor and upper floors are forced air).
I've noticed that in very cold temperatures, the radiant heat (in slab) in the basement struggles to keep up.
Because the radiant heat is fed by poly-B in the basement, the system is two closed loops (not sure the terminology here). With the "boiler loop" isolated from the "radiant loop" that has all of the poly-B hosing in it. Sounds good- protected from oxygenation and corrosion.
The problem seems to be that the average temperature of the water on the radiant side seems quite low, and the average temperature on the boiler loop seems quite high (70C vs around 40C). From what I can tell, the heat exchanger is not able to increase the radiant loop temperature enough in colder weather.
Has anyone encountered this problem? Are there better heat exchangers? Do heat exchangers wear/corrode over time causing a degradation? Is this type of low efficiency common for a heat exchanger?
Plumbers?