Caporegime
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- 13 May 2003
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- Warwickshire
IN that case wouldn't you much prefer a system + unvented?
Combi boiler, or condensing?
- Thread starter alexthecheese
- Start date
In a 4 bed house you're best of with a system boiler and a mains flow cylinder. Probably overkill for your personal usage but its appropriate for the house size. High, balanced pressures, no cistern or f and e tank, and pump and pressure vessel (for primaries) all within boiler so saves more space.
Have a 4 bed house and a valliant 937 and it works really well so far. we have 2 small children so baths every evening and hot water needed quite a bit (a 5 and 3 year old cause a lot of mess that needs to be cleaned up!). The design of our house made us want to move the boiler and remove the hot and cold water tanks so we went with a condensing combi. Hot water output is enough to run the heating and a shower at the same time, and fill the bath as quickly as when we had a hot water tank.
We have only had it a little while, and not gone through the winter with it yet, but very positive so far.
We have only had it a little while, and not gone through the winter with it yet, but very positive so far.
Caporegime
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- 13 May 2003
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- Warwickshire
Any downsides to unvented, aside from installation costs?
The Valliant 937 width & height is about the same, it's around a extra 200mm in depth though.
I suggested the Valliant 937 as it's a all in one, but if space available then a Valliant 624 or similar & a megaflow cylinder is my usual suggestion, as it gives you mains pressure hot water.
But, as already mentioned, it's probably overkill for your personal usage but its appropriate for the house.
I suggested the Valliant 937 as it's a all in one, but if space available then a Valliant 624 or similar & a megaflow cylinder is my usual suggestion, as it gives you mains pressure hot water.
But, as already mentioned, it's probably overkill for your personal usage but its appropriate for the house.
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One thing that's overlooked is if you live in an older house or in a hard water area, is the state of your mains water pipe. I live in a 1960 house in London, with an old lead pipe furred up with fifty years of limescale. Luckily, access is quite good down the side of the house, so we got the mains pipe replaced with modern polythene when we redid our kitchen (they just use a pneumatic mole to run alongside the old pipe).
The difference in water flow rate was immense, and is maxing out the boiler's capacity. Looking at the old pipe, I'd say we've got three times as much cross section now, and we've even had heating service engineers momentarily confused between our hot/cold taps because the water flow through the boiler is so strong. And of course there's the benefit of not having lead pipes any more.
So if you're in an older house and you're willing to spend a bit of money, you can get a lot more performance out of your boiler by replacing the mains water pipe. If you're limited by what you can put into the boiler, you'll be limited by what you can get out.
The difference in water flow rate was immense, and is maxing out the boiler's capacity. Looking at the old pipe, I'd say we've got three times as much cross section now, and we've even had heating service engineers momentarily confused between our hot/cold taps because the water flow through the boiler is so strong. And of course there's the benefit of not having lead pipes any more.
So if you're in an older house and you're willing to spend a bit of money, you can get a lot more performance out of your boiler by replacing the mains water pipe. If you're limited by what you can put into the boiler, you'll be limited by what you can get out.
Soldato
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- 10 Oct 2006
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Out of interest why would you spec a combi boiler with a cylinder for hot water ? I always thought this is what heat only or system boilers are for ?
Hot water at mains pressure, plus it's takes ages to fill a bath and turning on another hot tap will effect the flow to all the other outlets with combi.
With a megaflow or similar cylinder, you can fill a bath in a few minutes, it's also handy were you have two bathrooms,with a combi it takes considerably longer.
If you haven't the the space for a seperate cylinder, then a Vaillant 937 is a good compromise if you want a combi.
Soldato
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- 10 Oct 2006
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Was just curious why you would spec a combi boiler along with a cylinder as the Valliant 824 is combi boiler ? I would have expected a cylinder with a Valliant 624/630/637 system boiler or am I reading your post incorrectly ?
