Boiler Minimum Flow Rate
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Phill Peck
That's why I suggested he just buys a new pump and fits it.
It will be quieter and he can **** about with the variable speed as much as he likes.
When he sick of resetting the OH stat he'll set it to constant speed 2 and we'll all crack on with our lives.
It will be quieter and he can **** about with the variable speed as much as he likes.
When he sick of resetting the OH stat he'll set it to constant speed 2 and we'll all crack on with our lives.
You having a dig mate? I know what variable speed is the clues in the title. I was just stating a fact.
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The OP's boiler doesn't have pump overrun, so the pump stops as soon as the boiler goes out. There is no flow when the boiler is off, so the question of minimum flow when not alight does not arise.
As the boiler has a fixed output it requires a fixed flow rate. However, when TRVs turn rads on and off the head will vary. So the operating point on a fixed speed pump will also vary and the flow rate could reduce. An automatic bypass would overcome this.
As the boiler has a fixed output it requires a fixed flow rate. However, when TRVs turn rads on and off the head will vary. So the operating point on a fixed speed pump will also vary and the flow rate could reduce. An automatic bypass would overcome this.
If your gonna post stuff like
perhaps you should change your name to "captain of the bleeding obvious"
perhaps you should change your name to "captain of the bleeding obvious"
The OP says his boiler is an FF 60 and gives a link to the MI for an FF260.
So he probably has an FF260 which as you say David has no pump over run as provided.
However, the OP seems convinced he needs to know the minimum flow rate when the burner is not lit.
So the only conclusion is that he has fitted a pump over run device himself ( but not told us about it ).
Just because the burner is off doesn't mean the pump isn't running.
P
Phill Peck
I did think that, but a slower pump speed would only lengthen the off time.
Yes, that will happen if the boiler stat has turned the burner off, but there is still a call for heat from the room stat & programmer.
What's wrong with that? Provided the water temperature is above the room temperature, the rads will still be giving off heat. I don't know the hysteresis of the boiler thermostat, but its typically about 10C. So if the burner has gone off, but the pump is still running it will only take a few minutes for the water temperature to drop; the burner will then relight.
If, on the other hand, you are thinking about the boiler going out and the pump stopping, due to the room stat or programmer, that is not a problem; if it was, the manufacturer would have fitted a pump override. The reason there isn't one is that the water content of the boiler (3.65 Litres) is sufficient to absorb the heat given off while the boiler cools down with the pump off. Modern condensing, modulating, boilers may have a water content of about one litre, so they are equipped with pump overrun.
But the OP specifically was asking about the system flow rate through a bypass when both motor valves were closed.
With both motor valves closed the boiler should not be lit !
No he wasn't.
No he did not.
Well Pin, I appreciate that you are well qualified to interpret the English language but in this instance I will disagree with you over what he wanted to know:-
And the mention of the zone valves?
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