Megaflow and CH installation

[Dan Robinson]

OSO for the hot water cylinder.

As for 37kW in a 3 bedroom house - that is fricking nuts!! Do you play football in these bedrooms? Do they have their own micro-climates

My 4 bed detached I think I have said before can manage on 12kW. Maybe a bit more if its snowing.

 

[patman209]

Thanks for the replies - I was recommended earth Ariston or Main as a cheaper alternative to Sadia by the first chap who I rad round to give me a quote.

I also used the calculator for what boiler size I would need - mine comes out at 14.7KW which is a lot less than the 37 or 31KW recommended to me, but I think that only includes heating requirements, as opposed to hot water requirements too. However If I am having an unvented cylinder for megaflow, would I still need to add on hot water requirements to calculate boiler size or could that requirement be included in the calc for heating?

 

[D_Hailsham]

I also used the calculator for what boiler size I would need - mine comes out at 14.7KW which is a lot less than the 37 or 31KW recommended to me, but I think that only includes heating requirements, as opposed to hot water requirements too. However If I am having an unvented cylinder for megaflow, would I still need to add on hot water requirements to calculate boiler size or could that requirement be included in the calc for heating?

If you used the Whole House Boiler Size Calculator, the 14.7kW will automatically include 2kW for heating the hot water - unless you set it to 0kW.

As the water coming from an unvented cylinder does not have to be heated immediately, unlike a combi boiler, there is no need to have a high output boiler. If you want a safety margin go for an 18-21kW boiler, but make sure the minimum CH output is well below 12kW. For example:

Ecotec 637: 12kW - 37Kw - Unsuitable
Ecotec 618: 6.7kW - 18kW - Suitable

There are, of course, other boiler which would be suitable.

 

[patman209]

thanks a lot, the 618 is the one I was looking at following some of the messages further up this thread and using the boiler size calc.
Its also a few hundred quid cheaper than the 637.

Thanks

 

[gaswizzard]

Ecotec 637: 12kW - 37Kw - Unsuitable
Ecotec 618: 6.7kW - 18kW - Suitable

Not according to the last few fitted.

612. 3kw-12kw
615. 3kw-15kw
618. 3.8kw-18kw
624. 5.2kw-24kw
630. 5.8kw-30kw
637. 6.4kw-37kw

 

[ALEC1]

but if you can't dissipate the heat through the radiators or the cylinder coil there is absolutely no point in oversizing the boiler...the only people who benefit are the manufacturers and the supply chain!

 

[gaswizzard]

but if you can't dissipate the heat through the radiators or the cylinder coil there is absolutely no point in oversizing the boiler...the only people who benefit are the manufacturers and the supply chain!

Faster warm up time being one of the benefits , 2kw for HW cylinder is a joke , even more so when I read the HW and heating should be staggered in favour of a smaller boiler.

 

[ALEC1]

thats the only benefit but is it worth the extra cost..almost certainly not...

in addition if the OP is using compensation controllers there will be no need to heat things up quickly!

 

[mysteryman]

...and it will be on water priority, so it doesn't ever heat the rads and cyl at the same time. Therefore, in line with current advice and practice, you size the boiler for the central heating load only.

 

[D_Hailsham]

Not according to the last few fitted.

612. 3kw-12kw
615. 3kw-15kw
618. 3.8kw-18kw
624. 5.2kw-24kw
630. 5.8kw-30kw
637. 6.4kw-37kw

WB need to keep their web-site up-to-date.

I should have checked the installation manual, which agrees with your figures.

 

[gaswizzard]

...and it will be on water priority, so it doesn't ever heat the rads and cyl at the same time. .

Just the ticket for a large family with hot water usage at peak times , if it's anything like my household then CH won't get a look in for around 3 hours.

We will have to agree to disagree MM.

You can put your WC where the sun don't shine Alec. (excuse the pun )

 

[gaswizzard]

WB need to keep their web-site up-to-date.

I should have checked the installation manual, which agrees with your figures.

No disrespect DH but if you were an installer then you would have all the LATEST info at your fingertips , the only consulting is with the MIs.

 

[gaswizzard]

, in line with current advice and practice, .

..........and that can go to the same place as Alecs WC.

 

[ALEC1]

if it's anything like my household then CH won't get a look in for around 3 hours.

what lousy system design and you call your self a professional!

 

[mysteryman]

...and how it's done in most of the rest of the world. Size the boiler and the cylinder and its coil properly for a good job.