We've got a dual boiler - whatever one of those is. I know it isn't a combi boiler which I had in my last property and I want one again.
If I was to buy a combi boiler can it be fitted with my current heating system? Would the fitter remove the water tank - assuming we don't need a big tank of hot water anymore? Any ideas how much all this would cost? Are there specifications that we need to know about with a combi boiler?
We've got 9 radiators to run off it so do we need a certain output?
Thanks in advance for any help :)

There were a couple of threads on this a while back (they might turn up in the search). The laws have changed recently and you now have to have what is (in the opinion of all the different plumbers we had round) an inferior condensing boiler installed. All the plumbers we had talked at great length about the cons of them, the only pro being the slightly better efficiency. We managed to beat the deadline though and got a decent one installed.
Try a search for the previous threads....

Are combi boilers and condensing boilers the same?

Are you better of sticking with a traditional boiler with a tank?

The reason Im asking is that my dad said he thought his boiler was obsolete and getting parts would be difficult (I think its about 15 years old) so even though there is nowt up with it he was going to change to a combi.

I've not heard of a 'dual boiler'. Well, if you want to get ideas, wander into your local library and see if you can get hold of this book. "Reader's Digest of DIY". It will tell you all the different types of boilers, and what ppl use it for.

If I was to buy a combi boiler can it be fitted with my current heating system?
- A person needs to come out and give you a quote to see if they can fit whatever boiler you want to the existing pipe setups. (Btw, British Gas does a FREE quote.)

Would the fitter remove the water tank - assuming we don't need a big tank of hot water anymore?
- You can always ask if the fitter will get rid of the hot water tank for you. Never assume they will do this, that and the other. Always get a quote of specific jobs. So both parties are aware. It saves any arguments later.

Any ideas how much all this would cost?
-Costs will vary from company to company, only because of what you ask them to do. I got quotes ranging from 2k (local sheffield comp) to 4k (BGas). I realised the difference was because BG said they will change the pipe works too, whereas other company were just going to install a condensing combi boiler. It pays to know what you are asking for. Companies are not out to cheat you really, despite the way the media portrays it. (That DIY book helped me a lot in understanding getting a system that I wanted for my own preference. i.e. reduce costs in long term. Environmentally friendly. etc.)

Are there specifications that we need to know about with a combi boiler?
- Not really unless u want to be a plumber.

We've got 9 radiators to run off it so do we need a certain output?
- Yes. But the engineers will figure it out. They have this formula and things. I found it once on some energy saving website once. You don't need to know really as a consumer. Cos they should spec u and give u the right boiler for the correct output. They won't tell you such details, cos it's too technical, and not necessary for you to know anyway. Boilers go by wattage. As long as they give the right wattage for the size of rooms you have, then it's okay.

I myself had a condensing boiler installed. (Standard now, apparently.) The hot water tank disconnected. (Yet to be removed though, cos it had to be dried.) Though it means that both my c. heating AND water comes from the same boiler. The two do not run separately. My old systems had a hot water tank allowing you to have the two on separately. Something to consider maybe ?

If u like, I can recommend the company that did mine. PM if you're interested. It pays to shop around though.

The new regulations mean that only in very specific circumstances can a condensing boiler NOT be fitted in a residential property. You can research combi-boliers, but you are unlikely to be able to (legally) have one fitted.
Get 3 different plumbers in for quotes/advice.
The guy who did ours was very good, can't remember his name atm, it may come to me and I'll add it in a bit. Did the whole job in a day - remove/replace boiler, remove immersion heater, remove water tank, all associated works.

Btw, it does help to consider what you are putting in. For example, I know that a lot of new builds are now opting for a combi-boiler, but then both heating and hot water depends on this one machine. If anything happens to it, you will have neither. My condensing boiler have two radiators which will 'always' be on, even in the summer. I cannot turn it off. Well, I can reduce the heating output, but then it may not work as efficiently at the rate that it should as the manual says. I also have new radiators inputted, so it controls the temperature in each room without controlling it from the boiler, or from some control panel. If I planned to stay in the house in the long run, maybe I would've opted for something that does heating and water separately.

We find the benefit (extra space in our bathroom and attic room) of not having an immersion heater and water tank (plus the benefit of a never-ending, mains-pressure shower) outweigh the potential that if it breaks down we have no water or heating. It's far less likely to break down than our old boiler!
Also the thermostatic valves on the radiators are great, and the radiator that has to be "on" all the time is in the bathroom - where we always want it to be warm anyway!

Well, I have to admit that being a new boiler, it's under warranty and things. So less likely to break down. (Well, it shouldn't !) I have to admit, that because it's a 'sealed system' (?) that I have this lovely hotel-like power shower in my bathroom now, which I love to bits. :) It just runs off the mains. With my setup, 'condensing combi boiler' (?), the radiators that are forever on are in the bathroom, kitchen, and hallway. The hallway does get heated up nicely in the winter, and now I don't have a condensation problem as well, which I did used to have. I think my bill are quite reasonable too, need to double-check for this winter gone.

As a complete innocent to all this, shouldn't you be able to turn ALL your radiators off if you want to? Isn't it a waste of power to run them when you otherwise wouldn't? :confused:

Yes, but the system is thermostatically protected too I believe to stop it completely blowing up.

Yes, but the system is thermostatically protected too I believe to stop it completely blowing up.

Isn't that a fault with the system then, if it needs to heat radiators unnecessarily?

No, it's how it works. I could be wrong (I am no plumber) but I believe you choose one (or more) radiators to receive "full blast", you have the rest on thermostatically controlled valves. The whole system is also on a timer. Thus, you set the heating to come on at a preset time, if all the living areas reach their thermostat-set temp, and the boiler is still on (the timer hasn't switched it off), flow is maintained through the "constant" radiator(s) until such time as it may be needed in the others (when the temp drops and the valves open).
Think of it this way - it's inefficient to periodically light a boiler, heat ALL the water and circulate it. By maintaining a constant, small amout of very hot water, it is more efficient and gets "routed" when needed.
I think...

Well, mine is a sealed system as well, if I recall. I had some pressure problem the other day, and had to turn some valve to let off the pressure a little.

Well, I dunno the ins and outs, but roughly guess that even with a conventional traditional hot water tank (with a thermostat), you still need to heat it. My hot water now comes from the radiators. Presumably the 3 which are constantly on. Yes, I have hot water all the time in my house, as I set it to a particular temp on the boiler, and it gives me that temp. With conventional boilers or system setups, I'm sure the hot water still comes from somewhere, and that it's kept at a certain temperature so you can have hot water all the time ?

Condensing boilers are said to be one of the efficient type of boilers though. Hence the government introduces that really, and made it as a standard. Yes, I once found a list of the models, as some are more efficient than others. (I'll try and dig this out again, if ppl are interested.)

One thing I think I gotta watch out for is my shower. Cos I had a part replaced. (Ok, I broke the shower head cos I got curious... =p ) The guy did make a comment about the pressure being too high for one of his customer that it blew the shower head out ! >.< lol... So I gotta watch out for that really. Other than that, it's a good ssytem for moi, and it's still under warranty.

List of boilers for comparison in terms of efficiency
http://www.sedbuk.com/cgi-local/dynamicv.cgi?page=boiler8

Energy Saving website on tips and products
http://www.est.org.uk/myhome/

My hot water now comes from the radiators. Presumably the 3 which are constantly on. Yes, I have hot water all the time in my house, as I set it to a particular temp on the boiler, and it gives me that temp.
I'm pretty sure it's a slightly different "circuit" - I hope my hot water doesn't come through my radiators (I saw the colour of the sludge drained from the old "closed" system). Could be wrong though. I'd struggle to explaing the sheer number of pipes connected to the boiler mind. Perhaps a plumber can enlighten us?

Roll on the plumber! :thumbsup:

The hot water is on a different circuit to the heating - you wouldn't want water out of your radiators. With a combi boiler your hot water is heated as needed. Some higher end ones do have a small storage capacity so hot water is a bit quicker - some people have to wait a minute or so depending on boiler and set up.

If you have TRV's on your rads then you'll usually need some sort of bypass so that a minimum flow of water through the boiler can be maintained while it's firing. It can be done by leaving a rad without a TRV on it as in the above cases or a bypass circuit can be put in.

The connections to a combi boiler will be heating flow, heating return, cold main, gas main, domestic hot water, pressure relief valve and in the case of a condensing boiler a condesate drain.