Think we need a new boiler - no combi experience

[snoggle]

We are having an en suite built, and have a traditional vented system. The cylinder would have to be moved as part of the job, system is old, so builder has advised to get a new combi boiler.

How does a combi cope with running 2 showers, can you use at same time? What about when running a shower and turning a tap on? Are there any particularly good models? How much would we need to spend to get a decent performance (doesn't need to be super-powerful but want it to be pretty good).

Any particularly good or bad shower types for a combi?

We have a mains flow of about 20l per min we think. Any advice appreciated.

Yes it is possible we have 2 showers in our house and can run both without any noticeable reduction in water flow.
When running one shower turning on one tap makes no difference but turning on two does make an impact
BUT
that is my house.
In order to acheive this you MUST HAVE:

1. really good mains water pressure (can be measured by your plumber/anyone who comes to give you a quote)

AND

1. boiler with big enough output.

The third important factor is how the pipes are run.

Similar story here to MrsTara when it comes to two showers. We had a Worcester put in when we had a small extension 5 years ago and it has been great. We had the whole heating system replaced (our old radiators were huge but rubbish) and it cost just under £5000 for removal of old boiler / tanks, new boiler plus radiators for a 3 bed semi with an extra study and bathroom in the extension. Our house is warmer and our usage is lower.

You can run a shower and hot water tap at the same time on our combi, but the pressure does reduce a little on each. If you want to accommodate two showers running as once, talk to your installer about this and as already said go for something with a higher output, ie higher kw capacity.

We had our Ideal combi for ten years and it broke down that many times in ten years. Our engineer couldn't repair it the final time and Ideal wouldn't do a call out as they'd stopped making some of the parts. Their new boilers might be better, but personally I would never buy another.

As our old boiler broke down in the middle of winter we got a few engineers out to quote, giving us the choice of how quick we got it replaced. Their was a 50/50% split in recommendations, Worcester Bosch and Valliant. I checked and Worcester Bosch continue to make parts for at least 10 years after they discontinue a range, Valliant do it for 15 years. We went with Worcester Bosch as we had more faith in the engineer and it came with a 7 year warranty. We've had it just over two years now, we're really pleased with it and have had no problems.

You will notice a drop in water flow when you run two showers or run a tap and a shower. We have a Worcester 42cdi boiler and can't run two showers together, well we can but the water flow is terrible, we can run another tap or have the washing machine on though and although you notice the drop in flow it isn't bad. The installer recommended our 2nd shower was electric because he said in his experience both showers will be terrible if running together, he was right they are. He said if we wanted to go down the route of running two showers we would need a water tank along with the boiler. We had to turn down our water pressure as the shower seals kept coming out due to pressure, the shower was only rated for 5bar but we had just over 7bar coming through the pipe at the shower.

Thanks everyone, will need to have a chat with plumber. Re a second electric shower, would that definitely improve the situation? I had assumed that since electric ones also require a certain flow rate, they would compete with the mains supply to the boiler and might not be enough flow? Is that not how it works?

installers like combis because they can bung them in quickly, then run off and count the money.

A combi is especially suitable for a single-occupancy house where there will only be one shower or tap in use at a time. For you....

Fill a bucket at the kitchen sink, time it, calculate how many litres per minute you have.

Well we're certainly not single-occupancy :o

Yes, they are indeed recommending it as the easy option- building works mean we would need to resite the airing cupboard and move all the pipework, for a system which is quite old. The builder said that would be about the same price as the installation of a new combi, and would save us the headache of where to put an airing cupboard. But that said, we do want a system that works adequately as well, and I just feel a bit nervous about a combi.

Flow rate is about 20litres a minute as measured by kitchen sink and washing up bowl. Is that about average?

20 litres is quite good, and is more than an ordinary combi can heat.

However it would be very suitable for a conventional boiler plus a Megaflo or similar pressurised cylinder.

If your old boiler works, it could still be used as the heat source. A more modern condensing boiler will be more efficient, and most likely more powerful.

We're having the megaflow system put in that PJ mentions. We're getting rid of the airing cupboard and the unvented cylinder is going into the loft (it can go anywhere, but straight up is easiest in our situation). We're keeping the boiler but it's not too old anyway. It's a Worcester-Bosch.

For the record we had a Worcester-Bosch combi at our old house, fitted new and never had a single issue for 7 years we lived there. There was only 2 of us though (4 of us now!).

The unvented system is an interesting thought. Would installation of that be easier than moving existing cylinder? Ie it can just go straight up into loft in whatever position is easier rather than round walls? Do you need to replace pipes?

I would have electric shower too, more for if there was a boiler breakdown so you can still wash. The thing I don't like about combis is how long it takes for the hot water to come through, apparently you can get ones with small tanks inside now that keep a small amount hot and send that first when you open the tap.

We have a combi, one electric shower and one mixer, and the 4 of us all love our long hot showers. We have not been disappointed.

When they took out the old boiler I got them to fit a small radiator in the cupboard and we put shelves in and converted it into a great airing cupboard.

At a previous house we has a 10 watt electric shower fitted which made it more powerful. It depends on how it fits into your existing electric layout, so ask an electrician to fit it.

Having our current 8.5 watt electric shower fitted cost me the princely sum of £34 (plus cost of the shower).

Do you mind me asking what kind of combi you have yegods?

RE unvented cylinder; in our case the cylinder could go straight up into the loft, just a case of extending the pipes up in that direction. The thing they had to check is whether the roof structure could support the weight of the cylinder, if not it will need strengthening to take the weight. They also had to check the mains water pressure and locate the stopcock to check the size of the incoming pipe to make sure that is big enough (it is but they will have to increase the size of the pipe from the main up to the cylinder IYSWIM).

Well we've opted for the megaflo! It's coming next week and will live in the garage. Hopefully the right choice, since there will be 5 of us all trying to shower in the morning when the kids are bigger....

Sorry, I missed this! I'll check and pm you tomorrow!

Hope you are happy with your megaflo. :)

Ours is a Worcester.

Just thought I would update- we are so pleased with out pressurised cylinder! Our main bathroom shower, which is old, decrepit and very cheap, now has the flow of a power shower. The pressure from the taps is just amazing, and no loss in having more than one thing on at once.

Can't wait to get en suite shower in now.

Oh, and the system itself is a thing of beauty if you like shiny pipes :o

Excellent! Thanks for update.