Hi,
Ten year old system that provides ~1500sq ft radiant heat and DHW. Heat side seems to work fine, but there is reduced DHW output. Essentially almost luke warm. I cleaned the main exchanger (the one with the burner) which was real bad. That helped some. I replaced the DHW temp sensor and DHW plate exchanger. That also helped some. The sensor had tons of scale on it. The exchanger not so much that I could tell. However, lots of scale throughout the system on the o-rings and seals on the heat side.
The behavior now is if I set the DHW temp to max (140 degrees) and turn on the shower (low flow), boiler DHW temp runs at ~129 degrees. Temp at the mixing valve is ~112 degrees (6 feet from boiler). I've got the mixing valve set to hottest which should allow 150 degrees. I just replaced the mixing valve as well. In the shower, I get fairly good hot water but it also fluctuates back into temps that are not quite hot enough. It's not consistent.
If I turn off the shower, DHW temp at boiler rises to ~145 and boiler shuts down. If I then turn on the shower, that hotter water will flow through the system, but then boiler temp will slowly drop back to ~129 degrees. Is this normal operation? Seems to me that with one shower open, the boiler should be able to maintain 140 or close to 140.
I've got a new diverter valve rubber flapper on order and plan to inspect the diverter valve and input DHW filter. But I'm wondering if the pump is going and not providing consistent flow across the plate exchanger causing temps to fluctuate. There's no noise or other indicators of a bad pump. No codes. Pressure is good. Do pumps fail like this? Is there any way to test output flow? I'm also wondering if the scale has fouled the main exchanger.
Any thoughts?
thx!
Ten year old system that provides ~1500sq ft radiant heat and DHW. Heat side seems to work fine, but there is reduced DHW output. Essentially almost luke warm. I cleaned the main exchanger (the one with the burner) which was real bad. That helped some. I replaced the DHW temp sensor and DHW plate exchanger. That also helped some. The sensor had tons of scale on it. The exchanger not so much that I could tell. However, lots of scale throughout the system on the o-rings and seals on the heat side.
The behavior now is if I set the DHW temp to max (140 degrees) and turn on the shower (low flow), boiler DHW temp runs at ~129 degrees. Temp at the mixing valve is ~112 degrees (6 feet from boiler). I've got the mixing valve set to hottest which should allow 150 degrees. I just replaced the mixing valve as well. In the shower, I get fairly good hot water but it also fluctuates back into temps that are not quite hot enough. It's not consistent.
If I turn off the shower, DHW temp at boiler rises to ~145 and boiler shuts down. If I then turn on the shower, that hotter water will flow through the system, but then boiler temp will slowly drop back to ~129 degrees. Is this normal operation? Seems to me that with one shower open, the boiler should be able to maintain 140 or close to 140.
I've got a new diverter valve rubber flapper on order and plan to inspect the diverter valve and input DHW filter. But I'm wondering if the pump is going and not providing consistent flow across the plate exchanger causing temps to fluctuate. There's no noise or other indicators of a bad pump. No codes. Pressure is good. Do pumps fail like this? Is there any way to test output flow? I'm also wondering if the scale has fouled the main exchanger.
Any thoughts?
thx!