Two Boilers

[toasty]

I'm thinking of fitting 2 x 30Kwh boilers in my house.
I notice the gas meter says max flow 6m^3 per hour, which seems to equate to about 60-odd Kwh.

Has anyone here got experience of loading a meter so close to it's limit? Do I run the risk of one boiler switching off / modulating down due to insufficient gas.


I have no other gas appliances, and yes both boilers will at times be on together.

Cheers
-Dan

 

[muggles]

6m3/hr is 64.6KW, so if your boilers are true 30KW then you'll have a bit in reserve. The meter should deliver what it says it does, if it doesn't then you should be able to get it replaced.

Are you sure you need 60KW of heating? Sounds like a hell of a lot...do you live in a mansion? All respect if you do mind, just surprised at how much heat you need - who did your heat calcs?

Also, is there any reason why you aren't fitting one 60kw boiler? A properly modulating one will do much the same job - for example the ATAG Q60S 60KW boiler will modulate all the way down to about 9KW and makes use of weather compensation, which some people will have you believe is more efficient.

 

[BigBurner]

Look at the "input" gas rate of the boilers. Best have two boiler with a boiler sequencing controller. Boiler now around 24kW to 30kW are cheap.

Boiler sequencing for economical running. Look around there are many about.
http://www.warmworld.co.uk/026.html £190 + VAT
http://www.warmworld.co.uk/itemlist.php/clashist/-1,1,2/findclas/2/findchil/1

 

[Corgigrouch]

Crikey! The last pad that I visited that needed 60kW of heating was once owned by Oliver Cromwell, was as draughty as hell and the owner had a trailer on the back of his Bentley to tow his wallet around in

 

[doitall]

Two boilers on a header system is by far the best plan, and it's easy enough to get the meter changed to a U16 anyway if needs be.

 

[toasty]

Thanks Guys, that's really useful.

No I don't have a massive house, but like the idea of having two boilers and hence no one single point of failure.

Also the fact that the house should heat up a lot faster (given oversized radiators too and the correct controls)

And that hot water cylinder recovery will be quick even with the heating on at the same time.

 

[BigBurner]

Thanks Guys, that's really useful.

No I don't have a massive house, but like the idea of having two boilers and hence no one single point of failure.

Also the fact that the house should heat up a lot faster (given oversized radiators too and the correct controls)

And that hot water cylinder recovery will be quick even with the heating on at the same time.

Yep, you got it.

If you want real backup have an override on the boilers to by-pass the sequence controller, if that fails. You could also have them on different mcbs etc. You can go on, and on though.

If you have thermal storage, have each boiler directly connected to the cylinder (not via a header). The recovery rate will be brilliant. 60kW being pumped in as water is being drawn off. This means you can downsize any cylinders. A 60kW combi give instant DHW at around 25 litre/min to give an idea of the recovery what is being pumped into the cylinder. A 40 litre heat bank cylinder would actually do.

 

[toasty]

Thanks all.

 

[bengasman]

It is a bit, however, like cars. If you have a good brand and maintain it properly, you really don't need a second one.
You will save a lot of money and a lot of hassle if you just get a good RGI to do the job for you

 

[BigBurner]

You will save a lot of money and a lot of hassle if you just get a good RGI to do the job for you

The treads on this forum indicate that these are few and far between.

 

[Deleted member 105431]

You will save a lot of money and a lot of hassle if you just get a good RGI to do the job for you

The treads on this forum indicate that these are few and far between.

as you are not qualified at all you are certainly not one of them are you bigbullshit?

 

[Agile]

Thanks Guys, that's really useful.

No I don't have a massive house, but like the idea of having two boilers and hence no one single point of failure.

Also the fact that the house should heat up a lot faster (given oversized radiators too and the correct controls)

And that hot water cylinder recovery will be quick even with the heating on at the same time.

Over sizing a boiler is a very silly thing to do as it greatly reduces the efficiency. It should be illegal but so far it is not!

When you get problems then remember that I "told you so!".

If you really must have two boilers then you should have a smaller one and a larger one and an intelligent controller! Perhaps 15 kW and 35 kW.

Boilers fail about once every 4-6 years if they are properly installed on a clean system and serviced/inspected anually!

Tony

 

[BigBurner]

You will save a lot of money and a lot of hassle if you just get a good RGI to do the job for you

The treads on this forum indicate that these are few and far between.

as you are not qualified at all you are certainly not one of them are you bigbullshit?

MODS: please ban this offensive idiot

He also spams a company.

 

[BigBurner]

Over sizing a boiler is a very silly thing to do as it greatly reduces the efficiency. It should be illegal but so far it is not!

He is not oversizing the boiler he is putting two in.

When you get problems then remember that I "told you so!".

he should ignore you.

If you really must have two boilers then you should have a smaller one and a larger one and an intelligent controller! Perhaps 15 kW and 35 kW.

Nonsense. Two value for money boilers and a sequencing controller. I doubt you have ever come across one.

If on a heat bank the size does not matter. a very large boiler, or two, can be used if heated directly.

 

[simond]

40 litre heatbank? What will that do exactly?

You will need more like a 600 litre with a 60Kw plate HEX to get the value out of the boilers.

Also this guff about sequencing controllers is a nonsense. Just remind me how reliable controllers are and what happens when they fail. That's right, you are building in another single point of failure.

If you must have two diddy boilers, just link them together using the manufacturer recommended pipework. If you add fancy controllers, you may as well have had one boiler because you've just taken the resilience away.

Sequence controllers have their place in commercial installations where there is usually a dedicated maintenance person, in a domestic situation they are an unecessary contrivance.