Standard heating boiler to combi
Discussion
Got a quote for converting old condenser boiler to a combi. Same position as current boiler boiler will be used, in the kitchen.
Old hot water tank to come out and pipework capped/rerouted/whatever.
Approx what sort of labour time and price would this be?
He's recommended the Baxi 800 Series Combi Boiler. I can get the boiler myself for £1400, including a magnetic system filter.
Old hot water tank to come out and pipework capped/rerouted/whatever.
Approx what sort of labour time and price would this be?
He's recommended the Baxi 800 Series Combi Boiler. I can get the boiler myself for £1400, including a magnetic system filter.
I have read several threads where people are replacing conventional boilers with combi boilers. Is it to free up airing cupboard space and/or to save money by only heating water when there is demand?
Combi boilers are slightly more complicated beasts but are they super-reliable these days?
Combi boilers are slightly more complicated beasts but are they super-reliable these days?
Combi boilers are great in the right situation.
I have a 35Kw Glowworm boiler I put in nearly 10 years ago & in that time its had one door seal, one control board (any boiler can have those) and a recently replaced diverter valve (which would be specific to a Combi I think - £60 part).
So overall its been reliable and efficient.
Before you put one in its only appropriate where you don't have a lot of people trying to use water in the house at the same time. Flushing a loo affects the flow of hot water because its all coming directly from the mains.
Secondly stick a bucket under your kitchen tap and see how long it takes to draw 10 litres from the cold (mains) tap. Its quite crude but unless you have more than 10-12 litres a minute I wouldn't use a Combi, you need better water pressure than that. 12-15 litres/minute would be better
Thirdly, look at the hot water flow rates of the boiler. You will tend to buy a bigger boiler with a Combi to get a higher HW flow rate but equally there is no point in using one that will provide 15l of HW per minute when you can only get 12 litres out the cold tap in the first place, buy the next size down.
I have very high pressure (5 bar) & flow rates & I've had to put a pressure reducing valve in to reduce the pressure (as required by my water softener). 3.5 bar hasn't really affected the shower much at all (I thought!) but the side effect of that has also been we've used a lot less water in the last year!
Whilst allowing for the required HW flow rate, buy the smallest one you think you can get away with because when it comes to the heating side you want one that will tick over at the lowest output possible. If you buy the right boiler that will accept Ebus/Opentherm boiler controls (that will modulate the boiler when its running the CH) then it can be operated much more efficiently.
In that case the minimum output of the boiler becomes of interest. One that will modulate down to say 4Kwh is going to be better than one that will only go as low as 8Kwh because it will tick along at a low output level rather than cutting on and off & that's much more efficient.
In hindsight I would have been better off with the 24 or 30Kwh version of the boiler I have for this reason.
Finally, obviously it frees up airing cupboard and loft space, speaking of which I'd put it in the loft if you could & win back a kitchen cupboard as well !
I have a 35Kw Glowworm boiler I put in nearly 10 years ago & in that time its had one door seal, one control board (any boiler can have those) and a recently replaced diverter valve (which would be specific to a Combi I think - £60 part).
So overall its been reliable and efficient.
Before you put one in its only appropriate where you don't have a lot of people trying to use water in the house at the same time. Flushing a loo affects the flow of hot water because its all coming directly from the mains.
Secondly stick a bucket under your kitchen tap and see how long it takes to draw 10 litres from the cold (mains) tap. Its quite crude but unless you have more than 10-12 litres a minute I wouldn't use a Combi, you need better water pressure than that. 12-15 litres/minute would be better
Thirdly, look at the hot water flow rates of the boiler. You will tend to buy a bigger boiler with a Combi to get a higher HW flow rate but equally there is no point in using one that will provide 15l of HW per minute when you can only get 12 litres out the cold tap in the first place, buy the next size down.
I have very high pressure (5 bar) & flow rates & I've had to put a pressure reducing valve in to reduce the pressure (as required by my water softener). 3.5 bar hasn't really affected the shower much at all (I thought!) but the side effect of that has also been we've used a lot less water in the last year!
Whilst allowing for the required HW flow rate, buy the smallest one you think you can get away with because when it comes to the heating side you want one that will tick over at the lowest output possible. If you buy the right boiler that will accept Ebus/Opentherm boiler controls (that will modulate the boiler when its running the CH) then it can be operated much more efficiently.
In that case the minimum output of the boiler becomes of interest. One that will modulate down to say 4Kwh is going to be better than one that will only go as low as 8Kwh because it will tick along at a low output level rather than cutting on and off & that's much more efficient.
In hindsight I would have been better off with the 24 or 30Kwh version of the boiler I have for this reason.
Finally, obviously it frees up airing cupboard and loft space, speaking of which I'd put it in the loft if you could & win back a kitchen cupboard as well !
I wouldn't change to a combi.
Firstly a cylinder allows using solar or cheap rate power to heat water.
Secondly, in the foreseeable future heatpumps will be in our faces, so we'll be wanting cylinders again.
Combis do have plus points, but I don't see enough to make it worth changing from one to the other, in either direction.
Obviously, in some cases the tank might be in the way or whatever.
Firstly a cylinder allows using solar or cheap rate power to heat water.
Secondly, in the foreseeable future heatpumps will be in our faces, so we'll be wanting cylinders again.
Combis do have plus points, but I don't see enough to make it worth changing from one to the other, in either direction.
Obviously, in some cases the tank might be in the way or whatever.
OutInTheShed said:
I wouldn't change to a combi.
Firstly a cylinder allows using solar or cheap rate power to heat water.
Secondly, in the foreseeable future heatpumps will be in our faces, so we'll be wanting cylinders again.
Combis do have plus points, but I don't see enough to make it worth changing from one to the other, in either direction.
Obviously, in some cases the tank might be in the way or whatever.
^ whs Firstly a cylinder allows using solar or cheap rate power to heat water.
Secondly, in the foreseeable future heatpumps will be in our faces, so we'll be wanting cylinders again.
Combis do have plus points, but I don't see enough to make it worth changing from one to the other, in either direction.
Obviously, in some cases the tank might be in the way or whatever.
Combi might mean gaining some space in the loft with removal of loft cold water tank as well as CH header and free up some space where the HW tank might be but when your water provider f
ks about with the mains supply it's nice to know you have 3 days supply (ish) sitting in the loftAlso combis are often massively over spec'd from a CH perspective due to HW needs
megaphone said:
It is essential you have the existing heating circuit properly power flushed before fitting the new boiler, have they included this in the cost? You also need to ensure they actually do it properly with a proper power flush machine.
I think power flushing has fallen out of favour a bit as it throws up too many problems., and it takes ages to do it properly. Usually they'll chemical flush.Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff