Hi all; my wife has advised me that we are getting a new bathroom suite! she would like one that has the taps in the wall rather than on the bath itself. The shop told her that we cannot do this at present as we only have a Gloworm Ultimate 50 boiler and an immersion heater, and not a combi. Couple of questions that I would like some help with please.
Does a combi need any more ventilation space around it or external venting than the present boiler (which is situated in the kitchen behind a false cupboard door)?
Can I run the central heating via a combi?
Cost wise, will a combi work out more cost effective than the current boiler/immersion setup?
How much should I be paying for a decent combi, and any recommendations on make and model etc? My wife likes lots of baths, so the immersion is on quite a lot, and obviously the central heating is now on a fair bit. To give an idea on costs, our electric bill per month is £52 and the gas is £36. I am in the process of swapping from British Gas for both to Powergen, saving £200 per annum, but that's another story :-). Any help appreciated, Regards John
It depends on the boiler and manufacturer. Most manufacturers have this info. on their web site if you look in the installer section. Don't forget about possible flue space.
Yes you can.
In running cost terms, yes, if you are using only electricity to heat the water at the moment.
Good ones are in the £800-1100 bracket.
Before you do anything else, check the water flow rate at the kitchen cold tap using a stop watch and a bucket. If the rate is less than about 15-20 litres/minute, using any kind of mains fed hot water may be disappointing.
Smaller combi boilers are quite limited on hot water production rate. It can be as little as 9 litres/min, with better ones achieving
15-18lpm. bear in mind that this is for a 35 degree rise in temperature, so in the winter will represent the total rate at bath water temperature. Normally a tank/cylinder based system will fill a bath very quickly, so as another test, using a bath tap adjusted to the rate of the intended boiler, time how long it takes to fill the bath. Smaller combis can take 15 minutes easily, so certainly ask your wife whether that is acceptable.
Another option would be to keep the existing boiler and heat the cylinder from it. This would be cheaper to run than the immersion and much faster to re-heat. You may need to replace the cylinder, but it would be cheaper than a new boiler.
Not sure I quite follow that. It may be the taps they have are of continental design and are intended to run on mains pressure hot water. They would probably still work with your gravity fed setup but at a reduced flow rate to that which you are used to. It will depend how far above the taps your cold water cistern is (i.e. the amount of "head" you have)
Note that a combi boiler is only one of several ways to get mains pressure hot water, heatbanks, thermal stores etc are also options. You can google back through this group for the many discussions on the pros and cos of combis and work out if one is appropriate for your circumstance... (be prepared for some long threads!)
No. They are all room sealed with regard flue gasses anyway. Most need space above to accommodate the flue exit (approx 20cm), and a variable amount around depending on the make and model of boiler. Some require practically none.
Yes. If you could not then it would not be a combi but a multipoint water heater.
From a running cost point of view then it most likely will. Especially as modern boilers are far more efficient in general than the older ones. Your gloworm is down in the 73 to 79% efficiency range according to the SEDBUK database. A modern condensing boiler would be 95%+. So all things being equal, you could expect to use 10 - 15% less gas with a modern boiler.
Whether you would ever recoup the costs of ripping out a functional system ten years (or however long) before its natural end of life and replacing with a cheaper to run system is debatable if it costs you a couple of thousand to make the change.
If you went for a good condensing combi then prices tend to be between
600 - 1500 ranging from small entry level to top end models. Have google back on this group for recommendations, but in general many of the continental makes are well favoured.
Those bills don't sound vast. I would expect that moving to gas water heating will perhaps knock 20 quid off the electric and add a fiver to the gas - all other things being equal. Allowing for improvements in boiler efficiency you may find your gas bill stays about the same and the electric goes down.
Hi John, I think I was getting confused with a multipoint and a combi. In our previous house(17 years ago now) it was a multipoint we had that gave hot water on demand. Excusing the ignorance, but is it a combi or multipoint we should be looking at? Many thanks for taking the time to respond, Regards John
View two combi boilers. One doing one zone of space heating (upstairs) the other doing another (downstairs). Each boiler will have a programmer/stat for each zone, preferably a Honeywell CM67, or equiv. Combine the DHW outlets just before the bath using non-return valves and a small shock arrestor expansion vessel, as per Worcester-Bosch Tech dept. It will fill a bath pronto and give good power showers for two showers.
With combi's the most important figure is the flowrate. 11 litres/min is fine for showes and the odd slow filling bath. Here is a recent post of mine...
For an even better flow rate and cheap too for what you get, assess using two Worcester-Bosch Junior combi's.
For high flowrates it is cost effective to use two Juniors and combine the DHW outlets. Worcester-Bosch will supply a drawing on how to do it, or ask me here. Two Juniors are available for around £1000 to £1100 depending on what sized units you buy. They have 24 and 28 kW models, you could one 24kW and one 28 kW. That is cheaper than the Worcester HighFlow 18 litres/min floor mounted combi and can deliver about 21.5 litres/min @ 35 degree temp rise and never run out of hot water. The highest flowrates of any infinitely continuous combi is 22 litres/min @ 30 litre/min temp rise, which is the ECO-Hometec which costs near £2K.
Have one combi do the downstairs heating on its own programmer/timer (Honeywell CM67 or equiv) and one do upstairs. No complex and space consuming zone valves used. Natural zoning, so you don't have to heat upstairs when you are not up there saving fuel. The running cost will be approx the same as a condensing boiler heating the whole house. No external zone valves either, and simple wiring up too. The Juniors are simple and don't even have internal 3-way valves.
If having two showers, have the shower split between the combi's to reduce influence from one to the other.
Also if one goes down you will have another combi to give some heat in the house and DHW too. Combine the outlets for the DHW bath pipes and all the baths you want very quickly and no waiting. Best have the showers on separate combi's.
Do not exceed the gas meter flowrate of 212 cu foot per hour. To calulate, e.g., a boiler is 100,000 BTU/hr "input". Divide by 1000 giving 100 cu foot per hour. Add up all the appliances.
The Juniors are not condensing combi's, yet overall heating costs will be equivalent to one condensing boiler as the upstairs will not be heated most of the time.
A win, win, situation.
Its advantages are:
- cheap to install.
- quick to install.
- space saving (releases an airing cupboard). Both can go in the loft, or at the back of the existing airing cupboard.
- never without heat in the house as two boioers are used.
- high flowrates (will do two showers and fill a bath in few minutes),
- No waiting for a cylinder to re-heat
- Natural zoning, one does upstairs and one does down
- hardly any electrical control work (running a wire to a programmers/stat and power to each,
- simple no brainer installation,
- minimal components used.
- less piping used
- cheap to run overall as upstairs would be off most of the time
Depends on what you are trying to achieve, and how much you want to spend.
I see you have several options, First cheap ones:
1) Ignore what the shop says, and install the taps of your choice with no change to the existing setup. May just work fine.
2) Find an alternative tap that is designed for gravity feed and proceed as per 1 above.
3) Do 1 above, and if the flow rate is not good enough, add a shower pump to the pipework to boost the pressure.
Most of those could be installed and running for a few hundred (much less if you DIY)
If you are looking to reduce the cost of water heating then:
4) Convert your hot water cylinder to be heated by the current boiler. This will need a change/addition of a programmer a hot water cylinder stat, and a 3 port valve. A bit of re-wiring and plumbing. Possibly also a change in cylinder. The go with 1, 2 or 3 as required. This will make the cost of heating the water lower and also reduce the time to heat. Cost to have done 250 - 600 perhaps.
If you really want to boost the hot water pressure all round the house, AND, you have the mains cold water flow rate as described in Andy's post, you could look at either a combi or a multipoint.
5) The multipoint would be in addition to your current boiler, and would let you dispose of the hot water cylinder, and probably the cold cistern in the loft. These seem far less popular nowadays since most people looking for Direct Hot Water (DHW) will go the combi route and get heating into the bargain. Cost of this with the removal of tanks and re plumbing etc could be 800 - 1200 perhaps
6) The combi will cost a little more (but not much) and will replace your current boiler. It will then run the Central Heating (CH) and the DHW. You will get running cost savings on your heating as well though. A decent combi fitted will probably cost anywhere from 1000 - 1800 for a decent performance boiler. Double that if you get BG to install it ;-) With the combi setup you will also typically convert your CH to a sealed system. See Ed's FAQ for details on this:
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mentioned before either of these will require a decent flow rate from your cold water main. If that is not available you may need to consider other options or upgrade the main.
Knowing a bit more about your household and usage patterns might also help tailor the advice a little. How many people, bathing how often, showers how often, how many bathrooms in action at one time etc.
My apologies to Mr. Orrett, but based on previous experience this may degenerate... However due to the nature of the questions it is probably worth cutting through some of the "spin" to get a more balanced view.
Remember the question here is can I have different bath taps! Chances are using (a) combi boiler(s) of any sort is going to be a very expensive way of doing what the OP wants.
As long as you skip over the limitations...
Not compared to changing a bath tap, and also much more expensive that re plumbing the hot water cylinder to be heated by the existing boiler rather than the immersion heater.
Compared to what? Starting from the situation of having no CH and no HW at all, then a combi may be quicker to install than a cylinder based system. Most people don't start from this point however.
Sometimes true.
Sometimes true. Not sure this is a big issue since the things should not fail that often.
Better than one on its own yes. Compared to a heat bank solution then probably not as good.
True. Although a fast recovery cylinder driven from a decent sized boiler will recover far faster than the immersion you are used to.
Can be archived with some valves for less money.
Might be an advantage if you are fitting it yourself and are clueless about wiring, otherwise a non issue.
No more or less complicated than plenty of other options. Personally I would have though changing the taps was _far_ simpler.
In the grand scheme of things not that much of an issue, sine you will be paying far more for labour to fit them than you will for pipe.
Assuming you don't need the upstairs heated during the day etc.
IMM also forgot to include:
Some disadvantages/limitations are:
You need a good cold mains flow rate
You may get longer bath filling times (especially in the winter).
You will have no stored water, so in the case of a boiler failure you are without hot water. In the case of water failure you would be without water. In the case of electrical failure you also loose HW as well.
Most combis can run the CH or the DHW, but not both at the same time. So if people are having a number of showers one after another, the house could start to get chilly. Also things like not turning off a hot tap completely could result in the boiler turning off the heating.
If you CH system is getting on a bit, you may find it does not transition to pressurised operation too well, and hence you start incurring more cost replacing the bits that spring leaks.
So in summary a win win situation for some people, in some circumstances. One size does not fit all.
It will morph into me, the knowledgeable one, "telling" you, the unknowledgeable one..
"spin" do you think I am the Tory party?
The subject says "Boiler cost comparisons". He wants better flow for a new bathroom, and is also generally asking about a combi boiler to fo DHW and CH.
Here it is again.....
View two combi boilers. One doing one zone of space heating (upstairs) the other doing another (downstairs). Each boiler will have a programmer/stat for each zone, preferably a Honeywell CM67, or equiv. Combine the DHW outlets just before the bath using non-return valves and a small shock arrestor expansion vessel, as per Worcester-Bosch Tech dept. It will fill a bath pronto and give good power showers for two showers.
With combi's the most important figure is the flowrate. 11 litres/min is fine for showes and the odd slow filling bath. Here is a recent post of mine...
For an even better flow rate and cheap too for what you get, assess using two Worcester-Bosch Junior combi's.
For high flowrates it is cost effective to use two Juniors and combine the DHW outlets. Worcester-Bosch will supply a drawing on how to do it, or ask me here. Two Juniors are available for around £1000 to £1100 depending on what sized units you buy. They have 24 and 28 kW models, you could one 24kW and one 28 kW. That is cheaper than the Worcester HighFlow 18 litres/min floor mounted combi and can deliver about 21.5 litres/min @ 35 degree temp rise and never run out of hot water. The highest flowrates of any infinitely continuous combi is 22 litres/min @ 30 litre/min temp rise, which is the ECO-Hometec which costs near £2K.
Have one combi do the downstairs heating on its own programmer/timer (Honeywell CM67 or equiv) and one do upstairs. No complex and space consuming zone valves used. Natural zoning, so you don't have to heat upstairs when you are not up there saving fuel. The running cost will be approx the same as a condensing boiler heating the whole house. No external zone valves either, and simple wiring up too. The Juniors are simple and don't even have internal 3-way valves.
If having two showers, have the shower split between the combi's to reduce influence from one to the other.
Also if one goes down you will have another combi to give some heat in the house and DHW too. Combine the outlets for the DHW bath pipes and all the baths you want very quickly and no waiting. Best have the showers on separate combi's.
Do not exceed the gas meter flowrate of 212 cu foot per hour. To calulate, e.g., a boiler is 100,000 BTU/hr "input". Divide by 1000 giving 100 cu foot per hour. Add up all the appliances.
The Juniors are not condensing combi's, yet overall heating costs will be equivalent to one condensing boiler as the upstairs will not be heated most of the time.
A win, win, situation.
Its advantages are:
- cheap to install.
- quick to install.
- space saving (releases an airing cupboard). Both can go in the loft, or at the back of the existing airing cupboard.
- never without heat in the house as two boioers are used.
- high flowrates (will do two showers and fill a bath in few minutes),
- No waiting for a cylinder to re-heat
- Natural zoning, one does upstairs and one does down
- hardly any electrical control work (running a wire to a programmers/stat and power to each,
- simple no brainer installation,
- minimal components used.
- less piping used
- cheap to run overall as upstairs would be off most of the time
I like oranges, so I can't go on holiday to Switzerland.
If you're happy with your current boiler, and it isn't already running flat out in the winter, you could always just replace your direct immersion tank so that it runs off the central heating. If you're lucky, the old tank may already have an unused indirect coil that you could use.
Sorry Christian; I don't see where you are coming from. The point of the question was the fact that the Bathroom retailer told us we couldn't do what we wanted, i.e. taps in wall and not taps on bath due not not having a combi boiler. The above is a statement of fact and not a question. The rest of my ramblings might not have made sense to you (or anybody else for that matter!). That was the point of posting; to get advice. I take your point about running the immersion tank from the central heating, and I will look into that. This still does not, however, answer the original point. Do we or do we not need a combi like the man said, or is he incorrect, and our current boiler (and water pressure, I presume) would be sufficient for the job? Regards John
Common sense should tell you that the salesman is talking out of his arse. On a wall or on the bath, all a tap does is turn the water from the pipe on and off, and the result will be the same from either location.
The real issue is whether your system can supply enough hot water at a sufficient rate to fill the new bath in a reasonable time (will the new bath be bigger than your existing one?). This is also not dependent on whether the boiler is combi.
If your new bath is a similar size to the old one, and you can happily fill it at the moment, you don't need a new boiler.
If you want bath taps on the wall at a height where you can reach them whilst sitting in the bath I do not understand why you can not use your existing boiler and immersion heater.
Thanks for that. Don't know why the guy in the shop insisted we need a combi. They are not plumbing merchants, so there would be no extra finacial gain for them.
At present we need both the immersion and the boiler to give us a decent bathful of hot water.
My wife wants one of these 'shower baths', the ones with a bulge at one end. I don't know capacities or volumes of our standard bath compared to a shower bath, but it looks to me like it would need a lot more hot water or end up with half a bath!
Thanks for taking the time to reply Bob, Regards John
Me neither Michael - I'm just going on what the bathroom salesman told me! Whether wall mounted mid bath taps need more pressure or something I'm not sure. regards john
Perhaps you were talking a cross-purposes then. It does sound like you could do with some improvements to your hot water system - but you would need to do it no matter where the taps are going!
A combi may not be the best solution, though. Most that I've experienced suffer from low flow rate, so it would take ages to fill a sink, let alone a bath. I know IMM will jump in with advice about high flow rate combis and ones with a bit of built in storage to avoid them having to fire up everytime you turn the tap on, and he's right - they have improved a lot over the years. However, it mostly comes down to your mains water supply.
Personally, I'd probably keep the traditional system (you'll then still have an immersion for emergency backup for when (not if) the boiler fails). You just need a bigger hot water tank.
Is the cylinder small? Does it take an age to heat up the cylinder with the boiler.
You will require serious surgery here. You will need a larger cylinder and power shower pump at least Providing your cold mains are good enough consider:
A Heat Bank (does away with the tank in the loft)
High Flowrate combi (does way with cylinders and tanks)
use two combi's to give a very high flow of instant water (does way with cylinders and tanks).
As your boiler is an old model and you need high flows, consider No. 3. seriously. See my current post on this.
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