Boiler suggestions

Mike-H · 17 Sep 2010

Got some quotes comping in this week for a new boiler, cylinder and rads (total new installation).

House is a 4 bed, but we're extending to 5. Downstairs there is 2 living rooms, dining room and kitchen (this will be knocked down and extended). House will have 1 family bathroom in future, 1 ensuite and 1 donwstairs cloakroom/WC.

Guessing i need a decent size boiler and tank. They have all suggested closed vent i think. What boiler should they be offering and what ctylinder?

Sorry if a bit vague but I am not exactly a plumbing expert. Just want some assurance that they are quoting correctly for my house.

Mike.

Boilerman2 · 17 Sep 2010

Would this be Gas, LPG, oil, biomass or bio-oil ???

mickyg · 17 Sep 2010

let the installers suggest the products then come back. You can tell alot about an installer by what he installs

Mike-H · 20 Sep 2010

Gas.

Unbelievable. 3 quotes received. All suggest Vaillant 637 boiler, but diff cylinders. tall 210 litre cylinders to fit in cupboard space. Prices were diff by £4000! I was quite suprised to see such a difference as they all quote same boiler.

Can't see a reason not to go with lowest price if the boilers are the same.

kevplumb · 20 Sep 2010

Can't see a reason not to go with lowest price if the boilers are the same.

the quality of the installation might not be tho

mehran · 20 Sep 2010

though I find it interesting they all quoted the same boiler dont get fooled in to that way of thinking.

cylinders vary just as much as boiler in quantity and price as, can even cost more than the boiler.

then controls which cost vary wildly as well

even fittings, I like to use full bore lever valves which can cost £4-6 each compared to some 99p guarantee to leak after year ball-o-fix POS

it is easy to quote lower using the cheapest of the cheap but much hard to do a good job with quality stuff that will last.

I not going to tell you go for the most expensive but just make sure you know what you are getting.

Agile · 20 Sep 2010

Some others on here would not always agree with me about this. Apparently they can guess the water supply characteristics with testing !

I would say that anyone who quotes for an unvented without testing the mains water dynamic flow rate is not worth considering ( unless he realises his mistake and rushes back if you tell him he has got the job ).

You really need 20 li/min as a minimum with a dynamic pressure of at least 0.5 Bar and preferably 1.0 Bar.

Even running a cold tap you cannot guess what the test results are going to be although it can be so bad that it can be seen that it will never work.

I assume you want to use as a minimum two showers at the same time.

Without seeing your house that boiler power seems rather high. Its cheaper to spend money on insulation and not on an oversized boiler which will consume more gas.

You did not say how many people live there. More than three and I would suggest a cylinder larger than 210 li.

Tony

Mike-H · 20 Sep 2010

Is gledhill 210 litre unvented cylinder any good? That is the cylinder suggested by cheaper quote.

Top end was offering a Vaillant 210 unvented cylinder.

Mike-H · 24 Sep 2010

Agile said:
I assume you want to use as a minimum two showers at the same time.

Without seeing your house that boiler power seems rather high. Its cheaper to spend money on insulation and not on an oversized boiler which will consume more gas.

You did not say how many people live there. More than three and I would suggest a cylinder larger than 210 li.

Tony

Yes we may need 2 showers at once. We are currently Mum, Dad, 2 yr girl and a growing bump. If that ones a girl then I guess we will need 2 showers at same time.

The gap where cylinder will fit is only 57cm across so I do not know if i an fit anything above 210litre.

As house will be 5 bed next year with an ensuite and more rads etc. I have been told the Vaillant is suitable.

Any thoughts?

mehran · 24 Sep 2010

a good quality tank which is 57cm across is the OSO super S, goes up to 300L

gledhill is firmly set at the lower end....

as for the size...well that is a bit more tricky. if you get a 210L tank then the the water will be stored at 60 degrees but you will and cold water to make that comfortable to wash which will make it last longer...then you got the re-heat time. the faster the re-heat the smaller tank can be because it can recovery quickly.

saying that i have never fitted a tank bigger than 210L as it does most people

also need to know what flow rate you got, less then 20l/m cold it is not work a unvented tank unless you pump from a cold water tank.

for the boiler size put your final house size details in to this http://www.idhee.org.uk/calculator.html and it will tell you what boiler size is needed

Agile · 24 Sep 2010

I have never fitted anything smaller than 300 li.

Thats mostly because I have only fitted them in houses of four bedrooms or more and perhaps because since my installation charge of £460 is fixed regardless of the size of cylinder and the extra cost of 300li compared with 210 li is small and there is no disadvantage in having the larger size.

Tony

mehran · 24 Sep 2010

right...

no disadvantage other than the extra cost, extra space it takes up and extra weight you put on the floor?

also never knew the more bedrooms you have the more water capability you need? I always though you sized it for actually used.

I wonder does your £460 cover the cylinder coming through the ceiling?

honesty saying "I only fit 300L cylinders no matter what your needs" is completely backwards.

kevplumb · 24 Sep 2010

mehran said:
no disadvantage other than the extra cost, extra space it takes up and extra weight you put on the floor?

minor details

Agile · 24 Sep 2010

mehran said:
right...

honesty saying "I only fit 300L cylinders no matter what your needs" is completely backwards.

I did not say that!

All I said was that "I had". That means..............

If in the future another situation arose then a different situation might arise.

I calculate the optimum size not on the current number of people!

A five bed house with one old lady woudl work with 150li...........until she selld or dies and 10 people move in!

A four bed with three people would work with 210 li..............until they sell and 10 people move in.

So if the size of house woudl typically accommodate more than four then I size it accordingly and put me name on it.

I have NEVER yet seen an unvented with an installers name on it.

Of course a one bed flat would work with a 150li but most small flats are happy with a combi.

Tony

Mike-H · 24 Sep 2010

Do not really want a 'low end' cylinder. Sounds like 210 litre will do the job. I think I will stop at 2 kids and do not plan on selling anytime in my life (too much grief).

Would under floor heating in the kitchen extension effect the cylinder size? Or would this be a boiler issue?

Sorry about all the questions but you guys have been really helpfull and I guess thats what a forum is for.

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