Combi Boiler vs Cylinder

[RachelG]

Dear all,

I have just bought a semi-d (currently 3 bedrooms and 1 bath on 1st floor). I am planning to convert the loft to 2 extra bedrooms and also 1 shower at the loft. there will be 4 people living in the house and I want to make sure that there will be good hot water supply in both bathrooms and the kitchen.

At the moment, there is a BAXI 50He condensing boiler that the previous owner installed Aug last year. It is used together with a water cylinder on the 1st floor but it's badly corroded and need to be replaced.

I am wondering whether
1) Option 1 is to replace the BAXI with a combi boiler and remove cylinder (many friends said combi is only good for flats??)

2) Option 2 is to keep the BAXI and replace the cylinder with Megaflo, Santon or Vaillant. However, all these cylinders are so big that I won't be able to fit into the existing boiler cupboard.

Do you have any better suggestions?

Many thanks!

 

[corgiman]

1, only do this if you have one bathroom and your mains supply is good enough, get someone in to check it

2 again only if you mains supply is adequate

remember you can pump a normal cylinder you cant do this with a combi or unvented cylinder

My advise is get someone who you have had recommended in to discuss thepros and cons of this.

also seeing as the boiler is new it maybe best just to upgrade the cylinder

 

[gas4you]

For this size property I would alwasy go gor the unvented cylinder if you have good incoming mains pressure and a 22mm cold feed available to the cylinder from the stop cock.

If the Baxi is running ok then keep it. I would think you will need either a 170L or 210L cylinder. Un-vented cylinder will need qualified installer and notifying to building control.

Even big combis will only supply one tap at a time unless you go for a larger storage combi such as the Vaillant Ecotec 937, but it would be chucking out a fairly new baxi!

Also a powerful combi will need a much larger gas supply from your meter to it.

Storage combi would save cylinder space, but you would loose the aring cupboard function. Un-vented cylinder gives you a hot water back up via immersion if boiler goes wrong..

As you can tell you will have to think carefully about your decision as most of the answers can only come from your self and your hot water usage lifestyle

 

[corgiman]

For this size property I would alwasy go gor the unvented cylinder if you have good incoming mains pressure and a 22mm cold feed available to the cylinder from the stop cock.

If the Baxi is running ok then keep it. I would think you will need either a 170L or 210L cylinder. Un-vented cylinder will need qualified installer and notifying to building control.

Even big combis will only supply one tap at atime unless you go for a larger storage combi such as the Vaillant Ecotec 937, but it would be chucking out a fairly new baxi!

Also a powerful combi will need a much larger gas supply from your meter to it.

Storage combi would save cylinder space, but you would loose the aring cupboard function. Un-vented cylinder gives you a hot water back up via immersion if boiler goes wrong..

As you can tell you will have to think carefully about your decision as most of the answers can only come from your self and your hot water usage lifestyle

cor blimey you dont have have to be kwik to beat you gas

 

[gas4you]

Will you have room in loft after conversion to keep a cold water storage tank up there, you would need 2 x 25gal tanks or a 50 gal to supply these water demands, then just replace with standard cylinder as corgi says. A fast recovery type would be best as they are smaller but re-heat the water quicker, so in effect give you more usable hot water.

Beat me this time corgi. I'm tired and full of bacardi again

 

[RachelG]

Thanks! You guys are amazing.

For my understanding, if I go for combi boiler and save space, I won't have hot water problem by using Vaillant Ecotec 937?

 

[gas4you]

It still wouldn't be as good as an un-vented cylinder, but one of the best solutions if you want to go the combi route. They are a lump on the wall though, about 720H x 440W x 560D (approx) (mm) and need a very good wall to hang it on

 

[RachelG]

There is an old water tank (plus a header tank, not quite sure what this is) in the loft but it has to be removed or replaced. Can I remove both tanks in regardless of whatever system I go for?

 

[gas4you]

Before you make a final decision I would recommend you testing your cold mains pressure and flow rate, in a perfect world you would want at least 3-4 bar pressure and around 20-25 litres/min flow

 

[gas4you]

I would assume that the header tank is the f&e for the Baxi boiler so this would have to stay or the heating system converted to pressurised, shouldn't be a problem, assuming you are allowed to do this with this Baxi. I'm not familiar with this model

The large cold tank would go if you had a combi or un-vented cylinder.

 

[corgiman]

Before you make a final decision I would recommend you testing your cold mains pressure and flow rate, in a perfect world you would want at least 3-4 bar pressure and around 20-25 litres/min flow

listern to gas

you will curse the day you got rid of your tanks and installed a combi/unvented if you have a mains supply that tiddles out slower then you can wee

 

[RachelG]

Thanks guys! I will definitely check the pressure and flow first.

 

[ChrisR]

If you go for a combi consider having an electric shower somewhere.
They only use 4 litres/minute
and they mean you can still wash when the combi packs up.

 

[RachelG]

Hi guys,

The water flow rate in my house as well as my neighbour's is just 13 litres/minute. My understanding is that megaflo won't work well with the exiting rate and changing the pipe from the main to the house may not give me higher flow rate.

Am I right to say that it wouldn't make much difference whether I use megaflo or standard cylinder or combi? Is using standard fast recovery cylinders in both 1st floor and loft with a pressure pump the best route for me?

Many thanks!