Changing to combi-boiler

hello all

I asked this queston in a previous post but it was hidden within a separate topic, so i'll ask again.

At the moment i have a boiler which stores it's hot water in a hot water tank. The boiler is supplied with water from a header tank although i only have about 0.5m of head. The central heating is a closed system. I believe my cold water mains would be classed as high pressure.

I am wanting to put in a new kitchen and I am trying to decide what to do with the boiler. At the minute, it is sitting at eye level in full view, with all the pipes on show also. Needless to say, I want to hide them and the boiler. My options are to box in the pipes and put a cabinet housing around the boiler or to pay a plumber and have the pipes put behind the wall.

However, what happens if the boiler gets condemned next year. I would want a combi-boiler put in. What happens then? Is it as simple as connecting it up to the existing pipes? Something tells me it might not be. Last thing I would want to be doing is to rip up my new floor to put in more pipes. If so, I could maybe get the new pipes put in at same time just in case?

The boiler makes a funny vibrating noise sometimes, although i'm willing to put money on it that its the bearings in the fan that are doing that. I really can't afford to change the boiler at the same time as putting in a new kitchen.

Anybody got any thoughts/suggestions?

Thanks, Miguel

Reply to
Miguel
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Just been through a similar process.

They may be able to use the same pipes, but it's not a simple case of joining up the same way as it was. IIRC the way the standard boiler works is to effectively take a heating output and run it through the cylinder in the airing cupboard. That heats the water in the cylinder, which then goes to your taps. At no time does anything from the boiler directly mix with your hot water.

The problem is that a combi needs a hot water outlet as the water is actually heated inside it. Luckily in our case we had a hot pipe running to the washing machine under the boiler, so we just connected the combi boiler to that.

If you don't have that, and if you might want a combi at a later stage, then you need to allow for it now. The easiest thing would be to get a plumber to extend a hot pipe into the vicinity of your boiler and leave it capped so that the combi can be hooked up to it later. Naturally, get some plumbers in to quote for this to check that it's correct.

Also, make sure that you really do want a combi. I was surprised at the drop off in pressure when opening up more than one tap. I knew that it would drop off, but not that it would be so extreme that we are considering getting an unvented cylinder or heat bank.

We had a cupboard made around the boiler with the pipes boxed and skimmed and it looks fine. Burying the pipes in the wall would, I assume, be a lot more expensive.

Finally, don't use Moben :) .

Reply to
Bromley86

Another thought. Make sure that the boiler cupboard will be big enough for the boiler you eventually want, including any service clearances. i.e. choose the boiler now, even if you don't fit it.

It might be worth making sure that the boiler cupboard is easy to remove. I know that the clearances required for servicing are pretty small, but I'd imagine that installing a new boiler into an existing cupboard is made a lot easier if the cupboard can be removed and then replaced.

Reply to
Bromley86

Ok, so let me see if I have got this right

I thought I heard before you could only get combi boilers these days. you can still get the old style 'storage' boilers? I know what your saying about the drop in pressure. However having only 0.5m of head for my header tank, the hot water pressure couldn't possibly get any worse. It is a one bedroom flat so any combi boiler should be suitable I would imagine.

If I put this pipe in, then it should run from where the boiler sits to where the hot water tank currently is? (that would be very easy to do). Somethign that occurred to me, but which i'm guessing wouldn't work would be to 'reverse' the flow of hot water. ie, rather than hot water going from hot water tank - bathroom - kitchen, make it go from combi - kitchen - bathroom.

I don't have a huge budget so boxing them in would definitely be preferred. Point taken about clearance. The current boiler requires very little, I might need to look into what 'current' boilers tend to need.

Thanks, Miguel

Reply to
Miguel

Why do you think think the boiler will get condemned next year? How old is it?

If you look at brochures for current boilers you will see how well they harmonise with kitchen wall units. Can't see much advantage in boxing in, and a lot of disadvantages, but if that is what you want some will fit inside kitchen wall units. As far as the pipes being visible, park the microwave in front. Hey presto no visible pipes, but box them in if that is what you want.

Jim A

Reply to
Jim Alexander

You are confusing combi and condensing boilers.

Combi boilers produce instantaneous hot water.

Condensing boilers are more efficient. In most cases, any new boiler must be of the condensing type, which will require a drain pipe for the acidic condensate.

Combi boilers are generally good for showers (subject to your water mains flow and pressure), but can be very slow at filling a bath. If you retain a stored hot water cylinder, you can have an immersion heater as back-up, and with a vented hot water cylinder you can use a shower pump. With a combi, there is generally no back-up available if the boiler breaks.

Because combi boilers produce instant hot water they have a high demand for gas when running, so you might need a new gas pipe from the meter to the boiler location.

Ed Sirett's Boiler Choice FAQ goes into lots of detail.

Owain

Reply to
Owain

On Fri, 17 Aug 2007 03:56:21 -0700 someone who may be Miguel wrote this:-

You are confusing combination boilers with condensing boilers. It is a common mistake.

You can get a new boiler which will connect to your existing hot water cylinder and heating. Other than in specific circumstances it will be a condensing boiler. This would be the cheapest thing to do.

Combination boilers work best in one bedroom flats, where there is not likely to be more than one demand for hot water at a time. The advantage is that they avoid the space and losses of a hot water cylinder (though the losses are low if it is properly insulated), the disadvantage is low flow rate (particularly noticeable when filling a bath) and a single point of failure which robs the house of heating and hot water (an immersion heater in a cylinder is a cheap insurance).

There is more work, so fitting a combination boiler will be more expensive.

Do you take lots of baths? Do you find the hot water pressure too low at the moment?

Combination boilers have been over-sold and installed in inappropriate buildings by those who don't know any better (and some who no-doubt do know better). Like all things they have their good and bad points.

A combination boiler will also be a condensing boiler, but a condensing boiler is not necessarily a combination boiler.

Reply to
David Hansen

I do not expect the boiler to be comdemned next year. it was a 'what if' question, just trying to think ahead really. As they are just now, the pipes are really ugly and due to the layout of the kitchen it's not really an ideal place for putting something in fornt of them. I would hate to spend all that money on a new kitchen and have the pipes/boiler spoiling it

Miguel

Reply to
Miguel

Then that's what I will prob do if the need arises. I don't think In will be in the flat for more than 2-3 years so fingers crossed.

I put a jacuzzi in a year ago so at least once a week. Yes the pressure is definitely too low, but I put up with it and to be honest doens't really bother me too much. I'm pretty sure that a combi boiler would result in an increase in pressure in my case. I have considered installing a pump before but never got round to it

Thanks, Miguel

Reply to
Miguel

I was. I reckon i'll wil go with the condensing option if the need ever arises!

More reason to go with the condensing option

and again...

Thanks, Miguel

Reply to
Miguel

Increase in pressure certainly. Increase in flow quite probably too.

Reply to
Ed Sirett

The plumber can tell you exactly what is needed, but it wouldn't be necessary to go back to the cylinder.

You got it in one with the reverse-flow thing. In fact, I was going to put that in my first answer but thought it might be confusing :) . So all you do is take the hot supply for (say) the sink, spur off that and end somewhere accessible near the boiler.

When the combi is fitted, the plumber connects the hot-out to that pipe and does indeed reverse the flow. (He also caps off the old "start" point of the flow at the cylinder). If you opt for a condensing system boiler (i.e. as you have now but condensing), he just ignores the capped hot pipe and it just sits there. It won't affect anything, except that it cost you money to have it done. Just make sure that the caps are solid ones, unless you're willing to trust push-fits 10 years later.

Reply to
Bromley86

Remember that pressure and flow ain't the same thing. Apart from (possibly) things like showers it's the flow rate from an outlet that is important. It's quite conceivable that the flow rate from a mains pressure hot water system with poor mains pressure could be worse than one from a header tank type - even with only 0.5m of head - if that header tank type has well designed pipe runs. But it's unlikely. ;-)

Reply to
Dave Plowman (News)

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