# my baxi megaflo 32kw system boiler cycle - is this normal?

#### andreitone

Hi,

CH water temperature is set at 55 deg Celsius

this is how it cycles:

burner starts at 42 deg, heats the water at 58 deg in 10 seconds, then after 2 minutes the burner stops when the water reaches 60 deg.
the water temperature drops at 45 deg in about 30 sec, then after about 3 minutes the burner starts at water temperature of 42 deg.

I don't know exactly what temperature is shown on the display but I think is the return temperature.

I do think it's cycling too fast burner on/off and when the burner starts the water (return) heats up too quickly, I think it's because of the automatic integral bypass.

My question is:

Is this normal functioning?
Is there a way of adjusting the automatic integral bypass in this type of boiler?

Thanks

does it do this from cold, how many rads do you have do you have a room stat

It doesn't do this from cold, but in normal cycling. I have 7 radiators and no room stat yet, also no TRV's on the rads.

The rads are set as to have a 20 deg celsius differential on the return (so if 55 deg on the flow there is 35 deg on the return).

32kw is a big boiler for 7 rads how was this boiler sized, if you are trying to get 20c temp drop across rads by balancing lockshield valves then i think the bypass will be opening. Even at lowest modulation this boiler gives 9kw this is enough for many 3 bed houses

It doesn't do this from cold, but in normal cycling. I have 7 radiators and no room stat yet, also no TRV's on the rads.

The rads are set as to have a 20 deg celsius differential on the return (so if 55 deg on the flow there is 35 deg on the return).

Have you tried a higher flow temperature?

It seems to me that this boiler has been massively oversized!

For a start you could set the boiler to minimum output power although even that will be far too much!

Tony

It doesn't do this from cold, but in normal cycling. I have 7 radiators and no room stat yet, also no TRV's on the rads.

The rads are set as to have a 20 deg celsius differential on the return (so if 55 deg on the flow there is 35 deg on the return).

Have you tried a higher flow temperature?

I have tryed 60deg but did not watch it's cycle

For a start you could set the boiler to minimum output power although even that will be far too much!

Agile how can I do this?

32kw is a big boiler for 7 rads how was this boiler sized, if you are trying to get 20c temp drop across rads by balancing lockshield valves then i think the bypass will be opening. Even at lowest modulation this boiler gives 9kw this is enough for many 3 bed houses

thanks for the reply spudkey, would you think that a 10 deg temp drop across rads and lowering the CH water temperature will help the boiler not cicling as much?

It seems to me that this boiler has been massively oversized!

For a start you could set the boiler to minimum output power although even that will be far too much!

Tony

Tony can you set the boiler to minimum rate by adjusting the Min rate adjustment screw?

Tony can you set the boiler to minimum rate by adjusting the Min rate adjustment screw?

No, you call the installer and ask him to set it at the minimum output.

However, as he seems to have fitted a boiler which is totally oversized I would not expect that he can be trusted to do anything. I doubt that he is even CORGI registered.

Tony

In my country is very hard to find a professional installer...

Agile is it very hard to set it at minimum output? I think I saw something on the internet about this but can't find it anymore... I'd like to give it a try

I not sure the way I described is actually the way to do it. It might not be allowed,AIUI the adjustment screw is only for installers to adjust.

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