Advice on replacing heating system

[Dbman]

Hi,

I'm currently renovating an old Victorian 4 bedroom detached property and the heating system needs replacing. I have one main bathroom plus a separate shower room and 14 radiators throughout. It's not important for me to have 2 showers or a bath/shower running at the same time but it is important to have a high quality shower plus the ability to flush a toilet or run the kitchen tap at the same time.

I've had 3 plumbers out so far and all have recommended something different....really need some input.

First plumber recommended: Worcester Bosch 34CDi classic
Second plumber: Worcester Bosch System boiler with 250 litre unvented cylinder
Third plumber: vaillant Ecotech plus 937

I haven't got lots of spare cash but equally I don't want to spend money on a system that is inadequate for my needs.

Thanks

 

[doitall]

Whatever will depend on the incoming mains pressure and flow rate, has any of the 3 measured it.

On paper so far the 2nd plumber is in front, but a 250 ltr cylinder is well OTT, I certainly wouldn't expect one larger than 200ltrs.

What size boiler is he suggesting, and has any of them done a heat loss calculation.

 

[Dbman]

He was suggesting a 30kw system boiler.

Water pressure is about average and flow rate is about 18 litres per min from the outside tap.

Thanks

 

[Agile]

You seem to have had a good selection of apparently inadequate installers.

Any competent person proposing to fit a combi or unvented cylinder needs to measure the dynamic flow rate from your mains. An open pipe flow rate is not just whats required!

Two apparently tied to the Worcester brand and so unable to consider any other model.

Not even DIA can decide what size of cylinder you need because you have not told us how many people live there.

30 kW is a very large boiler power but it is possible that you will need one of that size if your heatloss is still high with solid walls and no serious attempts to solve heat loss and draughts.

Tony

 

[Dbman]

Thanks for the info, there's 3 people living in the house - 2 adults and one soon to be teenage boy. No heat loss was measured at all by any of the three people! House is typical Victorian large 18ft ceilings, loft insulation but not much else. Currently have original single glazed windows but these will all be replaced with new double glazing. Kitchen has been knocked through into conservatory (with no doors between main house).

Thanks,

 

[Agile]

An experienced installer can see the construction of the house and come to a good guess in many cases of the boiler power needed. But it should be calculated before confirming the order for the boiler.

Mains water dynamic flow needs to be measured!

Nor can an installer guess how many people live there!

The rule of thumb is about 50 li plus 50 li per person for stored hot water. That would give about 200 li BUT with that size house I would recommend a 250 li as just three people in a four bed house is only 50% occupied. In any case the marginal cost of the slightly larger cylinder is very small and there is insignificant difference in running costs.

So they got the cylinder size right!

Tony

 

[CBF]

i wouldn't go the combi route at all, but even to go unvented you need a pressure & flow rate test done, sometimes even in this day & age a conventional system with vented cylinder & roof tank is the way to go

 

[simond]

18 litres per min is a bit borderline in terms of getting value out of an unvented cylinder.

Probably best to look at a high flow combi.

The Vaillant 937 can give problems with its shift load pump (which is pain because you have to take the 837 off the shift load pack, 2 man job) Worcester Highflow models we have found to be more reliable.

And they have 7yr warranty if installed by someone who is a high volume accredited installer. Plumbers, maintainers and bathroom fitters dont typically install enough boilers to get this.

 

[hansthebear]

This forum is obsessed with unvented, based on what the op has said a high output combi would be ideal and more economical in my opinion.

Either way mains water flow/pressure needs checked before a difinitive recommendation could be made.

 

[doitall]

Whats wrong with an unvented cylinder. You don't loose the heating for an hour while half a dozen occupants have baths and showers.

You get a far better system, without have half a tonne of scrap metal hanging on the wall to fall of the kids.

And if nothing else at least you have a back up when the bean can breaks down.

Imagine living in a house with just 4 adults and no hot water for a few days, phew.

 

[RickyLee53]

To the Op, are you sure the ceilings are 18foot? Thats crazy high!

An experienced installer can see the construction of the house and come to a good guess in many cases of the boiler power needed. But it should be calculated before confirming the order for the boiler.

Mains water dynamic flow needs to be measured!

Nor can an installer guess how many people live there!

The rule of thumb is about 50 li plus 50 li per person for stored hot water. That would give about 200 li BUT with that size house I would recommend a 250 li as just three people in a four bed house is only 50% occupied. In any case the marginal cost of the slightly larger cylinder is very small and there is insignificant difference in running costs.

So they got the cylinder size right!

Tony

Please don't take this as an insult, or criticism. But why does the amount of people living their come into account? My farther in law lives in a 3 storey 6 bedroom house with 5 toilets/4 bathrooms. 3 people live there. My mum lives in a 2 storey house with 1 bathroom. 3 people live there. Would you spec a similar system?

Main reason I'm asking is because I have a terrible heating system. We purchased our house off a single old woman, the heating system is fairly new but inadequate. Is this a general room across plumbers, how much of the decision does it account for, more/less than the property.

Again, I'm not criticising just interested please don't take it the wrong way.

 

[hansthebear]

Whats wrong with an unvented cylinder. You don't loose the heating for an hour while half a dozen occupants have baths and showers.

You get a far better system, without have half a tonne of scrap metal hanging on the wall to fall of the kids.

And if nothing else at least you have a back up when the bean can breaks down.

Imagine living in a house with just 4 adults and no hot water for a few days, phew.

Because that is not what the op is speccing for

3 occupants

Do not require simultaneous hot outlets

 

[doitall]

But the OP has stipulated simultaneous hot outlets as a requirement.

 

[hansthebear]

He said it is NOT important to have more than one outlet going at once

Dont get me wrong im all for unvented When appropriate but this situation id be speccing a combi

 

[doitall]

but it is important to have a high quality shower plus the ability to flush a toilet or run the kitchen tap at the same time.