IS A COMBI BOILER SUITABLE

[littlecookie]

HI
IM HAVING A LOFT CONVERSION DONE SOON SO IM GETTING RID OF MY OLD TANKS AND BOILER AND GETTING A NEW SYSTEM
I'VE HAD A FEW PRICES FOR A COMBI BOILER FITTING BUT 2 FITTERS SAY A COMBIBOILER WILL BE FINE (WB 35CDI) BUT ANOTHER 2 SAY I NEED TO HAVE SOME SORT OF SYSTEM WITH A WATER STORAGE TANK
I HAVE 1 BATHROOM AND AN ENSUITE AND WITH MY LOFT CONVERSION I WILL HAVE ANOTHER ENSUITE SO WHAT IM WONDERING WHO IS RIGHT

1 BATHROOM
2 ENSUITE
2 ADULTS
3 KIDS
4 BEDROOMS

 

[JPC]

dont go with a combi with that size family (same as mine !!!)

what about a thermal store system for hot water and a sealed c/h system

 

[littlecookie]

SOUNDS EXPENSIVE

 

[CorgiIOW]

don't go with a combi, it will not deliver water to all the places all the time.
You should go with some form of H/W storage.

 

[LearnerPlumber]

If your current boiler is deemed large enough(output) to accomodate all that you are extending and the boiler is in good working order, there is no reason why you can't pressurise the system as the last guy said, this involves doing away with the tanks where I believe the loft conversion will be and keeping your hot water cylinder, full of nice hot water.

How about an electric shower in the conversion, guaranteed hot showers even if the kids want to bath concurrently whilst you want to shower.

So many options............Your spoilt for choice

A friend installed 2 combis, side by side that worked mighty fine......

 

[Agile]

Consider a combi feeding hot water to the loft bathroom AND a storage cylinder, ideally gravity cistern fed, feeding the lower bathroom.

Be wary of using any mains water supplied direct arrangement unless you have at least 25 litres per minute water flow.

I wonder how many of your "plumbers" bothered to check the mains water flow rate?

Tony

 

[littlecookie]

so maybe i could keep my boiler if its upto the job and get a new hot water storage cylinder and get rid of the tanks in the loft so all i will have is a boiler and a cylinder
the boiler i have is an ideal fitted when beezer built the house 8 years ago

 

[oilman]

You could, but only if you are rich. Pressurised water cylinders are expensive, and are not worth having unless you have a decent mains flow rate. What is the flow rate? You have fewer problems with a standard vented water system.

 

[littlecookie]

not sure what the flow rate is i think someone said about 26 litres not sure about that
what is a standard vented water system is that where you have tanks in the loft as i cant have them due to loft conversion, nope im not rich

 

[LearnerPlumber]

Excuse me, but where does she put the tanks in a loft conversion, build them their own little room..? Do away with the tanks , bring in the pressure vessel and electric showers where required, its cheap and efficient. Alternatively if moneys no object bring in 2 state of the art combis.......woooo...

 

[ACOperson]

26 l/m is just OK, that might be at just one tap though. Check flow at all taps and add up to get the total flow rate. Provided the pressure is good (over 2 bar) go for an unvented hot water system. Sure she'll lose a cupboard, but no matter how good the combi's are, if she's talking about running potentially 3 showers at once (1 bathroom, 2 ensuite) any combi is going to struggle.

Forget electric showers too, yes they're cheap but they are absolutely rubbish compared to a proper mains pressure system

Also, if you're considering keeping the existing boiler and pressurising it, make sure it's suitable. Don't go trying to put an expansion vessel on a boiler thats only suited to open vented systems!

 

[LearnerPlumber]

Your train of thought is almost there in what you said last, although, to rid you of the tanks you need to install a pressure vessel in their place or closeby. This will almost turn your old system into a COMBI...
I'm speaking in laymens terms NOT in Boiler Engineer terms, so I must add that a very competent plumber could easily carry out this undertaking. It is not that expensive for what you are aiming to achieve.
I hope this advice is of use to you.

 

[ChrisR]

there is no reason why you can't pressurise the system as the last guy said, this involves doing away with the tanks

You can't just pressurise the existing cylinder.

Loft conversions rarely occupy all the space and there is often eg a narrow gap at each side of a chimney. Cisterns are available in all shapes.

There is no simple answer to a question like this. You have to measure everything, weigh up the must-haves, the nice-to-haves, costs and practicalities.
For example, nobody would say an electric shower is the best to use, but the high kW ones are acceptable, give showers indefinitely, a backup for when a combi fails, and only use about 4 l/min from your mains.

 

[LearnerPlumber]

Sorry, but I forgot to say ALL THINGS BEING EQUAL that the vessel is quite small and through experience I can tell you that it can be put in a small cupboard (in the eaves..?) So you don't even know it's there...! Hope again this helps with the jigsaw...

 

[ChrisR]

What vessel - what exactly do you mean? Are you suggesting making the HW system unvented by adding a pressure vessel?