Vaillant, Ideal, Worcester: 10 year warranties!

[Blackspaven]

The heating output will probably be the same on both the 26 and 32, its just the hot water that will be better. You will be fine with the 32

These are the stats. Understand the flow rate bit but not what the CH side actually means. Little help?

 

[newcastle phill]

Its the Kw modulation.
Basically the low and high energy output

 

[Blackspaven]

Thanks, but I don't know what that realistically/operationally means. Guess it's something that the lay person isn't meant to know so they don't dispute installers; sounds complicated.

 

[GSAL]

With a combi the ch output is irrelevant really it's always going to be over sized. 2 bed semi will only be around 8-10kw heat loss so the max ch output will be turned down to suit. To size the combi simply measure your incoming mains water flow rate, multiply by 42 (desired temperature rise, 35 isn't enough) then divide by 14.29 = kw net output needed to heat your flow rate. This is so you don't buy a 40 kW but only have 8 lpm or a 24kw and have 15 lpm. I hope this is helpful.

 

[Blackspaven]

Thanks for the advice, but it's left me with a bit of confusion unless I'm not working the maths correctly: My flow rate is 13/14 lpm and the calculation gives a figure of around 40/41kw... but all the installers have been quoting for boilers WAY under that. Even the guy AT Worcester suggested just on the basis of the house the 30i which is only 24kw.

I must be missing summat, but thank you anyway.

 

[ShaunCorbs]

Combis you rate on hot water (within reason ) 30kw would be more than good enough unless you have rubbish flow rate , but then you wouldn't be having a combi fitted

 

[Blackspaven]

Okay, cool, thanks. Well, as I said, mine is 13/14 lpm so simply out of curiousity where does that stack up in the grand scheme of things in terms of what is a decent rate?

 

[ShaunCorbs]

An ideal flow rate would be 15-20 lpm

 

[Blackspaven]

Many thanks. There's always been an issue with flow in this house, south east water think I'm at the end of a run so the last to be supplied, and had to get rid of an electric shower as it kept shutting down in the morning due to low pressure cos everyone else is showering!

Still, fitted a mains thermo shower and never looked back.

Appreciate the help fella.