Higher rate boiler?

[bernardgreen]

However, this is pointless as a combination boiler is not suitable for the OP.

At least we can agree on that.

End of useful conversation

 

[Dan Robinson]

Yawn.

 

[Aquaheat]

Back to the OP

I would probably be looking at keeping the two boilers as you always have a back up should one fault.

Two boilers totalling about 36 should suffice and cover the addition of the 3 rads to be added basement area.

Unvented cylinder (as combination boiler is totally inappropriate for your type of property) with a DHW return in place.

Possibly a LLH setup to separate DHW/HTG

Zone each floor for increased efficiency.

Hard to design a system without seeing it but something similar to the above would suit I would've thought.

Jon

 

[muggles]

It's hard to specify a boiler size without knowing the size of the house. Saying it's "tall" doesn't help much. Give this a go and get back to us

A combi would be utter madness in a house that size; look at a regular boiler (or two) and an unvented cylinder

 

[Aquaheat]

@muggles from what I can gather it is a 3 storey house + basement area too so 4 in total.

Finished system would be around 13 rads across 4 stories and would think that there would be at least 2 bathrooms and ensuites due to amount of bedrooms.

OP can confirm?

Jon

 

[CrazeUK]

@muggles from what I can gather it is a 3 storey house + basement area too so 4 in total.

Finished system would be around 13 rads across 4 stories and would think that there would be at least 2 bathrooms and ensuites due to amount of bedrooms.

OP can confirm?

Jon

Hi, So there are:
6 bedrooms
2 lounges
2 hallway heaters
1 kitchen
2 bathrooms

+ 3 potentials for basement.
So 13 over 3 floors, at a push 16 over 4 (earlier i forgot to add the hallway rads).

Thanks

 

[picasso]

Get your pressure and flow into the building checked before you decide on any thing, the results will decide which route to take.

 

[D_Hailsham]

Give this a go and get back to us

The Baxi Whole House Boiler Size Calculator is a computerised version of the above document and is much easier to use.

 

[Aquaheat]

OK so with 16 rads now, 40kw may not necessarily be overkill. A proper heat loss calc would need to be done but I would still separate the total load over 2 boilers as this will allow for potential breakdowns and also offer savings as the boilers will be able to turn down to a lower kw if required as the system gets to temperature.

Pump in a standard boiler would probably not be up to the job so right pump sizing would be needed.

As said before

2 x heat only boilers

Unvented cylinder with DHW return for instant hot water

LLH separating DHW/HTG no need for hot water priority then and heating can remain on during reheat. Boilers operate at optimal efficiency due to being able to get the flow rates right through the boiler and not creating a massive temperature differential across flow and return.

Correctly sized pumps across primary and secondary circuits.

Each floor zoned and then possibly smart controls if you desire.

Should give you a highly efficient system that will give you mains pressure hot water instantly to your taps without loss of pressure should multiple outlets be used, the ability to zone off areas of the house not in use to cut costs and back up for both heating and hot water should one boiler breakdown and still have hot water should they both fail.

Again this is just guesswork from a forum and would need to be checked on site including pressures and flow rates as Picasso mentioned earlier but I don't think that system would be far wrong to keep you happy and warm.

Jon

 

[Agile]

40 kw into 16 rads?

That's an average of 2.5 kW per rad!

Some massive rads there!

I would expect more like 24 kW.

I use the annual gas consumption as a guide to what the actual heating needs have been.

Is it detached or terraced?

Tony