Hi All
I've read a lot of posts about DHW cycling between hot and cold but havent found anything specific to this boiler. The boiler is being used in a flat and is at the same level as the taps and shower it feeds. The shower is a thermostatic type but the hot/cold cycling affects the taps as well.
The flow rate for the kitchen tap is approx 5.8 litres per minute, the flow rate for the bath tap is approx 6.2 l/min
As is usually the case with the cycling posts I've read, I turn on the hot water tap and the boiler fires, the water gets very hot, then the boiler flame extinguishes and the water cools. Sometimes the water will go completely cold before the boiler fires again, other times the temperature sinks to "warm" before coming back hot. Having tried the kitchen tap just now, set to hot, fully open the temperature cycled between "very hot" and "acceptable for a shower" - I wonder whether the thermostat in the shower will upset the boiler by constantly varying the hot water demand in feedback and I end up with a situation where two thermostats are "fighting" rather than achieving equilibrium.
The boiler firing cycle doesnt seem to be even when the shower is in use. Sometimes the boiler will burn for a long time, sometimes only a short time. The delay between burns also varies. Here's an example of timings after setting the shower running at 38 degrees:
Burner ON for 12s
OFF for 14s
ON for 13s
OFF for 30s
ON for 17s
OFF for 19s
ON for 46s
OFF for 27s
ON for 24s
OFF for 5s
The central heating circuit does not get hot when DHW is in operation (from what i've read this would be a test of the divert valve correct functioning)
Having read the manual, I'm given to understand that this boiler should fire at maximum output until the desired temperature is reached, and then modulate the flame to maintain it. To me "modulate" would mean "vary but remain lit" - does this boiler modulate by turning the flame on and off completely? I don't recall this behaviour always being present, but the property has been empty and the boiler unused for a few months.. 4 days into returning to the property, this hot/cold cycle has started. It may also be worth noting that the problem was very apparent (i.e. water very cold) this morning at circa 830am but when I took a shower just now at 10am it was less pronounced; the water went cool, but not unbearable. I also have the flow tap on the shower set to a slower flow than she does (at 830) and my shower takes longer to cycle its temperature and is less of a pronounced swing
I've read a lot of posts about DHW cycling between hot and cold but havent found anything specific to this boiler. The boiler is being used in a flat and is at the same level as the taps and shower it feeds. The shower is a thermostatic type but the hot/cold cycling affects the taps as well.
The flow rate for the kitchen tap is approx 5.8 litres per minute, the flow rate for the bath tap is approx 6.2 l/min
As is usually the case with the cycling posts I've read, I turn on the hot water tap and the boiler fires, the water gets very hot, then the boiler flame extinguishes and the water cools. Sometimes the water will go completely cold before the boiler fires again, other times the temperature sinks to "warm" before coming back hot. Having tried the kitchen tap just now, set to hot, fully open the temperature cycled between "very hot" and "acceptable for a shower" - I wonder whether the thermostat in the shower will upset the boiler by constantly varying the hot water demand in feedback and I end up with a situation where two thermostats are "fighting" rather than achieving equilibrium.
The boiler firing cycle doesnt seem to be even when the shower is in use. Sometimes the boiler will burn for a long time, sometimes only a short time. The delay between burns also varies. Here's an example of timings after setting the shower running at 38 degrees:
Burner ON for 12s
OFF for 14s
ON for 13s
OFF for 30s
ON for 17s
OFF for 19s
ON for 46s
OFF for 27s
ON for 24s
OFF for 5s
The central heating circuit does not get hot when DHW is in operation (from what i've read this would be a test of the divert valve correct functioning)
Having read the manual, I'm given to understand that this boiler should fire at maximum output until the desired temperature is reached, and then modulate the flame to maintain it. To me "modulate" would mean "vary but remain lit" - does this boiler modulate by turning the flame on and off completely? I don't recall this behaviour always being present, but the property has been empty and the boiler unused for a few months.. 4 days into returning to the property, this hot/cold cycle has started. It may also be worth noting that the problem was very apparent (i.e. water very cold) this morning at circa 830am but when I took a shower just now at 10am it was less pronounced; the water went cool, but not unbearable. I also have the flow tap on the shower set to a slower flow than she does (at 830) and my shower takes longer to cycle its temperature and is less of a pronounced swing
