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Which type of boiler?

(20 Posts)
cat88 Mon 19-Jan-15 22:13:16

Anyone got any recommendations whether we should get a combi boiler or a condensing boiler with hot water tank?

We are getting an extension built so will be a 5 bedroom, 2 showers house. We currently have a back boiler that needs replaced. We have had different plumbers saying different things. We are told a combi would probably be ok but I am concerned about loss of pressure to the showers if anyone uses any water elsewhere. I am also concerned with 3 DC who LOVE long showers, how much hot water we will have. The boiler and tank are at least another £2K plus fitting cost. Anyone got any recommendations for our situation?

TalkinPeace Mon 19-Jan-15 22:18:02

I have a solar thermal panel, 240 litre tank and Vaillant boiler, all at mains pressure no roof tanks so that shower mixers work fine

in the summer (April to October) the sun does all my hot water.

PigletJohn Mon 19-Jan-15 23:00:34

2 showers at a time will be a bit weak with a typical combi. A bath will be slow to fill. If someone turns on a tap at the same time, or flushes a WC or starts a washing machine, the pressure and temperature will probably change. Combis are very suitable for small homes with one person in them. If you have five bedrooms you presumably have several water users.

Fill a bucket at your kitchen sink cold tap, time it, calculate how many litres per minute it delivers. Do the same at your garden tap and utility room tap and see which has the greatest flow. What is it?

Can you see the incoming waterpipe, and see what colour it is, and the diameter?

cat88 Thu 22-Jan-15 11:00:04

Thank you for your replies. Would love a solar panel but don't have enough roof space due to gables and dormers.

Piglet that is exactly what I don't want - years of being in the shower and getting drenched in cold water as someone elsewhere has turned on a tap/washing machine are a memory from my childhood!

Five people, 3DC who already spend AGES in the shower. We are doing the extension primarily to get another shower room as well as family room so I don't really want to skimp on the boiler nor over specify.

The incoming water pipe is copper and there are 2 copper pipes about 20 mm in diameter from that - I cannot see the actual incoming pipe due to kitchen cupboards. The bucket at the kitchen sink took 3.5 secs to fill 1 litre. Don't have a utility room (yet) and outside kitchen tap is inaccessible - blocked off by new extension and new one to be situated elsewhere.

I think we need to get a unvented cyclinder condensing boiler with megaflow based on our latest plumbing recc. Any thoughts?

cat88 Thu 22-Jan-15 11:00:04

Message withdrawn at poster's request.

cat88 Thu 22-Jan-15 11:00:23

Message withdrawn at poster's request.

cat88 Thu 22-Jan-15 11:00:24

Message withdrawn - duplicate post.

cat88 Thu 22-Jan-15 11:01:03

Message withdrawn at poster's request.

cat88 Thu 22-Jan-15 11:01:29

Message withdrawn at poster's request.

BikeRunSki Thu 22-Jan-15 11:06:03

We got a new boiler a few months ago. I don't think you can get combos anymore - or at least they are not recommended or considered current technology. We got a condensing boiler, Worcester Bosch. Happy with it so far!

cat88 Thu 22-Jan-15 11:19:52

thanks bikerunski - Worcester seem to do well in the Which best buys so thats good to know - do you know the size?

PigletJohn Thu 22-Jan-15 11:21:19

Almost all boilers are now condensing. Some of them are combis, and some are regular or system boilers, which will need a cylinder of some kind.

A combi is not very suitable for a larger home, or one with multiple users or multiple bathrooms. Opinions differ on this point.

It is very difficult to get permission to fit a non-condensing boiler.

PigletJohn Thu 22-Jan-15 11:28:34


yes, an unvented cylinder would probably suit you. Get the installer to measure flow and dynamic pressure to confirm your supply is adequate though.

Megaflo is a brand name, there are others.

In "Which" the top three boiler brands were Vaillant, Worcester Bosch and Viessmann. Plumbers and heating engineers spend a lot of time arguing which is best. I have a Viessmann, though they are less common in the UK so there are fewer approved installers outside large towns.

Look on the manufacturer's website for a local approved installer of the brand you are considering, there will often be a longer guarantee if you use one.

5madthings Thu 22-Jan-15 11:31:31

We jist got a veissman boiler, it is apparently the most energy efficient and did very well in which reports.

But we only have three bedrooms and one shower. Seven people though! It was fitted Monday and the difference is hearing and availability of hot water on demand is.noticeable, it's great!

5madthings Thu 22-Jan-15 11:32:08

Ours has a ten year guarantee.

PigletJohn Thu 22-Jan-15 11:41:55


it has a stainless steel heat exchanger, in a coil, and there is no reason I can see that it could ever corrode or get blocked.

5madthings Thu 22-Jan-15 11:48:38

Yes we chose it because of that, our old boiler was nine years old and died a death due to corrosion.

We have also had a special magnet thingy fitted to help with limescale as we are in a high lime scale,area which was also causing problems.

We paid £2200 to have the system replaced and flushed out etc. The old boiler could have been repaired but needed over £1000 spent on it, no way we're we spending that much on a nine year old boiler, we had already spent £500 getting it repaired less than a year ago and we had it serviced every year. It was an ideal? Boiler fitted under a gov scheme when we first moved in.

cat88 Fri 23-Jan-15 20:42:36

Thanks all, our plumber does recommend a veissman boiler - unvented cyclinder. Piglet thanks again i'll get him to do that.

We have an ancient boiler +20 years at the moment - how much am i likely to pay to get the system flushed out - is it necessary?

PigletJohn Fri 23-Jan-15 21:13:29

yes, absolutely. It is half a day's work with a powerful pumping machine and some chemicals. The installer will probably do it, or have an assistant, and bundle it into the total cost. It would cost some £hundreds if you had it done separately; double that if BG did it.

Look up your installer on the Viessmann website, if he has been on their training course he will be listed and you will get a longer guarantee.

And you will want a system filter, which will capture future circulating particles before they can accumulate into a blockage. Even after flushing, sediment will lurk in corners. Ask to be shown how to empty the dirt out and keep the instructions on top of the boiler. Once a month at first, reducing eventually to once a year. It is as easy as emptying a vacuum cleaner.

cat88 Sun 25-Jan-15 22:15:14

Thank you piglet. I think he is a Viessmann installer so will check on website. i'll also ask for the quote to include a system flush out and a system filter as well. thanks again flowers

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