hi all . I am having an extension on my house and will need to move my boiler. I currently have a 3 bedroom house and will be extending so that i will have an extra 2 bedrooms extra bathroom and also a utility room. i currently have a modena 80e combi boiler which looking in the book says that heat output is 23.8kw heat input 25.8. not sure what these figures mean and can provide more info if required. what i would like to know is seeing as i have to move boiler anyway will i need a larger boiler to heat my house and also two bathrooms. any help appreciated thankyou steve
will i need a bigger combi boiler
- Thread starter stevedunkgrass
- Start date
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D
Doctor Drivel
Keep it and add another combi.
The two combi approach using these combis, rather than: a powerful system boiler, unvented cylinder or heat bank and zone valves and stats to give a two zone (upstairs and down) heating system. In short using the energy available down the gas pipe rather than using a fraction of it and storing energy in space taking cumbersome cylinders that can expensively rot.
With two combis, one can do downstairs CH one upstairs, both on stat/programmers. One can do the DHW of one bathroom, one the other. Both combine the DHW to supply the bath giving over 24 litres/min fill rate.
The U6 gas meter will just cope with two combis.
CH Zoning is infinitely more simpler. Zoning with system boiler is cumbersome, complex, space consuming and messy.
Two combis will never run out of hot water, as will a cylinder, so great for multi-jet showers.
Tho combis has DHW and CH backup having two boilers, which one boiler will not.
The very fast heat up time, of 63kW being pumped into the house is highly significant to the normal 15kW in most houses. The combi boilers modulate the CH input too.
Two simple and highly reliable combis are less complex than three zone valves and stats in a cylinder and two heating zone setup.
The electrical control side is a doddle to do. Two sockets (or fused spur), one for each and a simple one wire to a stat programmer, switched on voltage free contacts at the clock. Or use wireless versions to get around Part P.
Reliability is extended as the two combis share the load so are used less.
If I was doing a new system with mains pressure hot water and two CH heating zones, I would certainly consider the two Atmos combi route. Every time I have costed two combis over a system boiler/unvented cylinder, two CH zones, the two combis always comes out tops is installation costs. Detractors whine that two combis is less reliable (maybe they are thinking of BIASIs. With the likes of say an Atmos combi(s) that is not the case.
The two combi approach using these combis, rather than: a powerful system boiler, unvented cylinder or heat bank and zone valves and stats to give a two zone (upstairs and down) heating system. In short using the energy available down the gas pipe rather than using a fraction of it and storing energy in space taking cumbersome cylinders that can expensively rot.
With two combis, one can do downstairs CH one upstairs, both on stat/programmers. One can do the DHW of one bathroom, one the other. Both combine the DHW to supply the bath giving over 24 litres/min fill rate.
The U6 gas meter will just cope with two combis.
CH Zoning is infinitely more simpler. Zoning with system boiler is cumbersome, complex, space consuming and messy.
Two combis will never run out of hot water, as will a cylinder, so great for multi-jet showers.
Tho combis has DHW and CH backup having two boilers, which one boiler will not.
The very fast heat up time, of 63kW being pumped into the house is highly significant to the normal 15kW in most houses. The combi boilers modulate the CH input too.
Two simple and highly reliable combis are less complex than three zone valves and stats in a cylinder and two heating zone setup.
The electrical control side is a doddle to do. Two sockets (or fused spur), one for each and a simple one wire to a stat programmer, switched on voltage free contacts at the clock. Or use wireless versions to get around Part P.
Reliability is extended as the two combis share the load so are used less.
If I was doing a new system with mains pressure hot water and two CH heating zones, I would certainly consider the two Atmos combi route. Every time I have costed two combis over a system boiler/unvented cylinder, two CH zones, the two combis always comes out tops is installation costs. Detractors whine that two combis is less reliable (maybe they are thinking of BIASIs. With the likes of say an Atmos combi(s) that is not the case.
thanks for both replies so far. the idea of fitting a second combi sounded like a good idea though limited for space next to where i was going to move boiler to. would also have to pay for 2 boilers to be fitted rather than 1. also it would cost twice as much to maintain so might now give that idea a miss but thank you for the idea. gas 4 you thanks for the reply with regards to the fact that 2 combis of one supply might be to much, deffo makes me not consider that option for time being at least. could you give any advice on whether my boiler will have enough power to heat a 5 bed house thanks
You need to do a quick calculation for the heat loss in your extended house.
Most combis, even yours at 23 Kw output, are big enough to handle a large property.
Combis are usually only sized for their HW output.
Most combis, even yours at 23 Kw output, are big enough to handle a large property.
Combis are usually only sized for their HW output.
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thanks look like i will keep existing boiler. might have a lok at how much a condensing boiler might save me though.
Got to admit I have 2 combi's & gas hob running off a u6 meter, one combi for the house & one for a 4000gallon koi pond, works perfectly, even when they are all on at the same time 
great reading guys hope you all dont mind me butting in as it my topic. alot of slagging going on especialy in the direction of dr drivel. he has tried to help out which was what i was after, if all of you slagging him could actualy either try and make a sensible suggestion as to whether replacing my boiler with a bigger one is a required or just the sensible thing to do. dont mind all the slagging if you are also trying to help me out with the original question at the same time.lol
back to the OP
the modena isn't a very good boiler and at only 80,000 Btu i wouldn't expect much from it. certainly not capable of running 2 bathrooms in my experience. the modena 102 and the F30 struggle!
as for 1 new or 1 additional, i would go with a vaillant ecotec plus 837 this would give a good flow to 2 bathrooms (may struggle with 2 baths simultaniously) and can run enough rads for most 5 bed houses with ease
or if you have a utility or boiler room the 937 (washing machine!) storage combi.
the modena isn't a very good boiler and at only 80,000 Btu i wouldn't expect much from it. certainly not capable of running 2 bathrooms in my experience. the modena 102 and the F30 struggle!
as for 1 new or 1 additional, i would go with a vaillant ecotec plus 837 this would give a good flow to 2 bathrooms (may struggle with 2 baths simultaniously) and can run enough rads for most 5 bed houses with ease
or if you have a utility or boiler room the 937 (washing machine!) storage combi.
D
Doctor Drivel
Moderator 5 said:
Well done Mod. Some people were disgusting on this thread.
Running 60Kw on a domestic meter can be a real problem. We have an issue with a customer for whom we have just installed a 37Kw (ecoTEC 937) and the working pressure is only 12mB.
SGN are saying that they do not have to supply 37Kw and the customer should pay for the main to be upgraded. Vaillant won't allow it to be connected and the delay has been very disruptive for our customer.
Hanging 60Kw on a domestic meter could result in disappointment. If you decide to go down this route (which I do not think is sensible for a whole raft of reasons) I suggest you get the view of the gas transporter first.
SGN are saying that they do not have to supply 37Kw and the customer should pay for the main to be upgraded. Vaillant won't allow it to be connected and the delay has been very disruptive for our customer.
Hanging 60Kw on a domestic meter could result in disappointment. If you decide to go down this route (which I do not think is sensible for a whole raft of reasons) I suggest you get the view of the gas transporter first.
D
Doctor Drivel
Take it up with them at a higher level, and get in touch with Ofgas too, and you may find they have too. 37kW is not a lot these days.
Thats rather less bullish that recently when you said that you thought that there was a legislative requirement for them to supply at the rated capacity of the meter and upgrade at their cost.
Tony
Rupert; if you modded efficiently and looked at past posts from the unqualified and legally incompetent Drivel, you would see who needs to be removed.
Perhaps DIY Admin ought to take note over his incompetent posts before you are sued by an unfortunate poster who is sadly stupid enough to be taken in by his codswallop.
The majority of us on here are fully qualified and experienced to enable us to respond to diyers in need of help.
Drivel isn't either Be it on your heads
Perhaps DIY Admin ought to take note over his incompetent posts before you are sued by an unfortunate poster who is sadly stupid enough to be taken in by his codswallop.
The majority of us on here are fully qualified and experienced to enable us to respond to diyers in need of help.
Drivel isn't either
Be it on your heads I think that you may find that Mod 5 is not Rupert ! ( Mod 4 ? )
He seems to think that he has to delete posts to satisfy his power complex!
He probably does the same thing at numerous other forums!
Tony
Edit, I may have muddles up mod numbers here!
He seems to think that he has to delete posts to satisfy his power complex!
He probably does the same thing at numerous other forums!
Tony
Edit, I may have muddles up mod numbers here!
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