36.6kw boiler and central heating pump speed

[dormermike]

Before changing the boiler output you need to use the Whole House Boiler Size Calculator to find out how large a boiler you really need. This will tell you which setting the boiler should be on.

OK understood - but does the data badge tell you anything useful ( you asked for it i think ). From what i can tell the rating hasn't been specified, so it could be any of the low/mid/max rating is my understanding correct?


Thanks

 

[oilboffin]

I would hazard a guess and say you have a surplus of about 12 kw of heat that you don't need I would see a good heating engineer and get the whole system reset properly

 

[dormermike]

I get the following:

The required boiler output is 35.63 kW

Thats if i specify unfilled cavity walls. The reason for specifying unfilled cavity walls is that the extended 90% of the side walls of the bungalow have 50mm polystyrene insulation board in place. The remainder including the front double bays are uninsulated. From speaking to cavity wall insulation companies there is nothing that can be done to "fill" the cavities (beads etc) because of the polystyrene boards.

If i go for the option of "filled cavity" i get the following:

The required boiler output is 26.67 kW

Both with a DHW requirement of 2kw (default option) as I have a bog standard 140 litre copper cylinder.

Cheers

 

[D_Hailsham]

OK understood - but does the data badge tell you anything useful ( you asked for it i think ). From what i can tell the rating hasn't been specified, so it could be any of the low/mid/max rating is my understanding correct?

I have had a Corgi chap look at the system, had it serviced last winter. I mentioned range rating at the time and was told not possible.

The fact that there are three possible settings shown on the data badge tells me that the output can be adjusted; it's not fixed. So the person who told you range rating was not possible is talking nonsense.

We don't know what the current setting is, but using the boiler Size calculator will tell you what the setting should be. You will need a Gas Safe Registered (no longer Corgi) engineer to check and adjust the boiler to the correct setting.

 

[dormermike]

Hi

I have looked into this by searching but asking the question too to see what the general feedback is.

I have a largish bungalow (dormer, approx 210sqm) with a ideal mexico 2 36kw boiler with open vented y-plan system. Stat in living room and TRV's on all rads (except a bypass rad).

On pump speed setting 2, I found the boiler would often fire for a very short period quite frequently and didnt seem long enough to possibly contribute any heat to the rads. I suspect this was because the water inside the boiler would get upto temp (setting 5 of 6) before the heat could be shifted away from the boiler so experimented by turning up to setting 3 and sure enough boiler seems to stay on longer, and rads get very hot very quickly.

I should add that on setting 2, all the rads got hot except for one which is the furthest I think, and on setting 3 this rad is definately hotter.

So, is it OK to leave pump on setting 3? I think the system is working better, but guess i'll know for sure when my bills arrive (if they are hugely increased i'll put it back to 2!! haha).

One thing I wonder is, would setting 2 work better if all the lockshields except for that one rad were throttled back a bit.. worth a try?

Thanks
Mike

So, going back to my original question, does that seem about right that pump setting #3 would work better given the size of the boiler? It seems to be cycling less which has to be a good thing doesn't it? Because more of the heat goes into the pipework rather than staying put?

 

[D_Hailsham]

So, going back to my original question, does that seem about right that pump setting #3 would work better given the size of the boiler? It seems to be cycling less which has to be a good thing doesn't it? Because more of the heat goes into the pipework rather than staying put?

You are probably correct. A 36kW boiler needs a high flow rate (47 litres/min) and the Grundfos 15/60 will struggle to provide this on setting 2, particularly the older versions. If you let me know the P/N and PC of your pump (on front plate) I can check the pump data.

 

[Agile]

Can you upload a picture of the boiler's data badge?

Here you go - thanks

Untitled

• dormermike
• 22 Oct 2012
• 1

So is it a 36.6kw and can the jet be downsized? Thanks

Most boiles are range rated by a simple screwdrived by an RGI.

Not normally necessary to change jets on a gas boiler!

Tony