4 story townhouse - Combi or Std boiler? Advice needed

[dm397]

Hi all,

Have been in our Victorian townhouse a year and the Boiler has just broken.
We're getting conflicting advice from friends / family so wondered if anyone else in a similar property or good understanding of boilers can advise us...

The boiler is on the ground floor, we have a shower room (with Power shower) on the top, third floor, main bathroom on second floor. 12 radiators throughout the four levels.

Should we replace our existing standard boiler set up with a Combi? Are they powerful enough to run hot water to the top - how powerful will it be? Apparently with a Combi we can no longer have a Powershower.

We're concerned that a Combi will mean our shower and baths will dribble hot water and they will take an age to run hot.

Also planning on a WORCESTER-BOSCH. Any thoughts on model really appreciated.

Many thanks

 

[muggles]

I'd recommend a system boiler and unvented (mains pressure) hot water cylinder provided your mains can take it, you need 20l/min minimum really to run an unvented. Alternatively look at the Rinnai Twinflow system. With the amount of hot water demand you are likely to have a normal combi simply won't keep up (although in a moment GaytonTanner, who posts on here but is not a heating engineer or installer, will come and tell you otherwise).

A combi would run hot water all the way to the top as the 'power' in that respect comes from your mains pressure rather than anything specifically to do with the boiler, but you're quite right in saying that it could take some time for the hot water to get up there.

With an unvented cylinder you could have secondary circulation installed, this would give you virtually instant hot water at all taps.

You wouldn't be able to have the power shower with either setup, you wouldn't need one either as the water would be at mains pressure (albeit with relatively poor flow from a combi).

Your installer will normally have a preferred boiler brand, WB are towards the better end of the market but there are other good and arguably better makes out there. Why did you want a WB specifically?

 

[dm397]

hi muggles, thanks for taking the time to reply to our post. really appreciated.

Planning on a WB as i've had them recommended by several friends who've had new boilers installed recently. Have hear Valiant are also good though.

I'm afraid I'm a complete novice with this so when you say an unvented tank, is this a typical hot water tank? If we went with the conventional boiler we were planning on increasing the size of our tank anyway so that we can get more than one bath out of it!

However my wife's still keen on the Combi boiler as it would free up space in our house. Is there a solution that could use a Combi and a secondary tank for additional hot water?

Thanks again for your advice.

Dan

 

[bengasman]

In general, a large combi would work fine for you, but the only real way of knowing for sure is asking the RGI that has been on site. In stead of asking us to judge it from behind a keyboard, you should find yourself a good RGI, and ask him.
WB CDI's are good, the other models are a lot less.
Vaillant is not a bad boiler, but the company is extremely bad for customer service, without a doubt the worst in the country.

 

[Nige F]

I'd With an unvented cylinder you could have secondary circulation installed, this would give you virtually instant hot water at all taps.

?

As you could with a conventional boiler/ cylinder setup . Do you really need unvented Domestic Hot Water...PS my alter ego is Gaylord- spanner, the forum spammer .. You do need a clued up + Gas Safe installer

 

[muggles]

An unvented cylinder is one that runs at mains pressure rather than from a loft tank like the cylinder you have now. The space the setup occupies should be a secondary consideration to the requirement to satisfy your hot water demand, yes you could just have a combi but you could also end up disappointed with the hot water performance. I don't quite see what you mean about having a 'secondary tank'...isn't this the same as having a hot water cylinder?

There are some storage combi boilers available which have a small built-in hot water store, these can give a higher flow rate until the store is depleted (often within a few minutes) then the flow rate is much reduced

 

[muggles]

An unvented cylinder is one that runs at mains pressure rather than from a loft tank like the cylinder you have now. The space the setup occupies should be a secondary consideration to the requirement to satisfy your hot water demand, yes you could just have a combi but you could also end up disappointed with the hot water performance. I don't quite see what you mean about having a 'secondary tank'...isn't this the same as having a hot water cylinder?

There are some storage combi boilers available which have a small built-in hot water store, these can give a higher flow rate until the store is depleted (often within a few minutes) then the flow rate is much reduced

A W-B 550 gives 25 litres/min and then drops to approx 17 litres/min.

To the OP. You have 1.5 bathrooms. You should check the water flow and pressure. If OK go for a high flow combi. He will never run out of hot water. You will not look back,

Aaaaand there he is, as predicted. You'll note that the WB550 he's so fond of loses one third of it's performance once the water store is depleted, which takes very little time.

And GT, re-read the OP, you'll see that there's two shower rooms and a main bathroom. You're right, a combi won't ever run out of hot water but that doesn't mean it can provide a high enough flow rate for the demand. Go back to your troll cave

 

[bengasman]

Dm397, never mind the funny remarks to gay tonnie, they are not aimed at you. The gay boy is a sometimes amusing, but mostly annoying troll who has no real knowledge about plumbing or heating.

The confusing bit for people like yourself, is that on the surface, g-t's comments seem to make sense sometimes but the reality is that they are no more than collations of stuff he finds on the internet.
Probably best to click on his name, and click the ignore button.

 

[mickyg]

To the op, IF you need a new boiler and if your happy with your existing setup and everything works fine, then just get a replacement heat only boiler to do the same job. It will be the most economical and the most reliable long term. Heat only boilers tend to have a longer lifespan. Additionally by having a standard system layout, any future maintenance and repairs will be easy and quick to carry out as standard system components such as pumps and valves and controls are sitting on most heating engineers vans, so you won't have to wait around for parts to be delivered.

 

[Nige F]

Micky- you are a Scholar and a Gent.

 

[JohnD]

Beware of your wife who wants a combi because it will give her an extra cupboard.

I suspect she has never sat reading a book while an ordinary combi slowly fills a bath; nor has she had a shower from a combi where the temperature and flow vary every time someone turns on a tap or flushes a toilet in another part of the house.

Run the kitchen, or garden, tap into a bucket; time it; and see how many litres per minute you get. That is important, because with an ordinary combi that is the maximum flow you will get at any one time, shared out between all the hot and cold taps in the house.

p.s. if you have a 4-storey house, and she has already filled all the cupboards and storage space, how long will it take her to fill one more?

 

[JohnD]

p.s. Combi boilers break down much more often than heat-only boilers.

This is very inconvenient because you will have no hot water at all (unlike a Cylinder which can have an immersion heater as backup)

 

[mysteryman]

It all depends upon your cold water main flowrate. Check this first.

 

[JohnD]

you aren't seriously attempting to deny that combis break down much more often?

or that it is particularly inconvenient when they do?

 

[mysteryman]

Breakdowns are not frequent occurrences on quality boilers properly installed.