There is a disagreement in another thread as to the adequacy of hot water supplies from combi boilers.
There must be lots of people here with them, so will these people please answer the question "Are you satisfied with hot water from a combi boiler, without extra storage".
I will start, because I look after a combi boiler in a semi commercial kitchen at the Curry Project. We are very satisfied with the Hot water there, especially because the hot water is food quality, because it is not stored. We can fill the urn up with water from the hot tap. I have had this confirmed by the local Environmental Health Officer.
| On Sat, 10 Sep 2005 10:18:33 +0100, Dave Fawthrop | wrote: | | >There is a disagreement in another thread as to the adequacy of hot water | >supplies from combi boilers. | >
| >There must be lots of people here with them, so will these people please | >answer the question | >"Are you satisfied with hot water from a combi boiler, without extra | >storage". | >
| >I will start, because I look after a combi boiler in a semi commercial | >kitchen at the Curry Project. We are very satisfied with the Hot water | >there, especially because the hot water is food quality, because it is not | >stored. We can fill the urn up with water from the hot tap. I have had | >this confirmed by the local Environmental Health Officer. | | | This is a pointless survey because | | 1) Most people here do not run semi-commercial kitchens
That is a downright daft comment. Many will have domestic installations, I only included it because for most hot water systems in the UK it is a * Very Bad Idea* to drink from the Hot water tap. I happen to know that Combis are different. | 2) Some people may have only used a combi boiler and have nothing to | compare it with.
I've managed perfectly well for many years by boiling cold water to make a hot drink. Or boiling water in a pan for cooking, etc.
And for a commercial kitchen most would have some form of 'still' to provide continuous boiling water.
Plenty will only have experienced a storage system with poor head so problems with showers, or a 'normal' size combi with problems when filling a bath. And many seem happy with an electric shower which gives inferior performance to even the worst combi.
So unless you've experienced a decent storage system which can do everything required of a hot water system - or had experience of a high flow combi - the survey is rather meaningless.
No it isn't. Suggesting that the factors that make a combi useful in a semi commercial kitchen would be important to a domestic user certainly is.
You wouldn't actually *drink* from the hot water tap because the water is at 60 degrees. If you were to use it for food preparation, it would almost certainly be boiled anyway. In terms of washing dishes, the issue is pretty much irrelevant. If they are washed by hand, then bacteria etc. would be transferred to the dishes in handling anyway. If a dishwasher is used, then almost all these days heat from cold water anyway.
In short, the potable hot water argument for a combi in a domestic situation is a very thin one.
Will they? You thought that 9lpm was fast enough to fill a bath. I think that 2-3 times that is becoming more reasonable. If somebody has only ever had the low flow rate of a combi or gas multipoint, they may not know that one can do a great deal better.
I think you are being unfair. The question was, how pleased are you with a combi, and *then* the OP went on to explain why he liked it. He never suggested all installations were in commercial premises.
However apparently you *can* drink it, if that is important to you.
Again the OP did not ask for *comparisons* but for opinions on each individuals experience. I drive a small car and am very happy with it but no doubt most Ferrari drivers would find it a bit of a drag but again, that wasn't the question was it ?
But the question was presumably about performance? So the car comparison is fair. Small cars use less fuel and are generally much cheaper to buy than fast ones. Same as small versus large combis. So a combi covers a vast range of products with different performance.
Of course. My point was that this is irrelevant in the context of domestic use.
... and this is meant to be a major decision making criterion?
That would be like asking small car drivers whether they liked their small cars when they had never driven a larger or faster one. Of course, they might not be able to afford a larger or faster one or have specific reasons for wanting a small one.
However, if you ask a question where an unknown proportion of the respondents have experienced nothing else better, it doesn't produce a very meaningful result.
For kitchen taps, showers and other low volume uses generally yes subject to not being on a water meter at the time. Stopping and starting a combi to rinse during washing up wastes a lot of water. For filling a bath a simple No. The combi I had was a 100,000 BTU gas model. Since moving we have a storage system and I prefer it.
Aside from the usual problems with self selecting surveys, I can give you a few answers to the question:
My own combi (35kW >91% (i.e. 32kW delivered to hot water) Ideal Isar)
General impression - the best combi I have used by far - good control of temperature at low flow rates, no surprises (slugs of scalding water etc), instant hot water Hot water flow rate - on the low end of acceptable Showers - very good Bath filling - moderate (depending on ground water temp)
This boiler replaced a poorly designed and implemented storage system. In comparison it is much better for showers, not as fast for baths, but can do more than one. The storage system suffered from lack of head, undersized cylinder, and very slow recovery times.
My Mums Combi (29kW 70% (i.e. 20kW delivered to hot water) Myson Midas)
General impression - reasonable control performance in use, temp control at low flow rates fluctuates, instant hot water, 'kin large box on wall
Hot water flow rates - unacceptably slow Showers - ok Bath filling - very slow (10 - 15 mins) System replaced a multipoint gas water heater. The combi has slightly better control at low flow rates (i.e. multipoint only worked when you turned the hot tap full on). The multipoint did not have the small internal store of the combi and so had a longer warm up time before producing hot water. It did however include flow regulation to maintain the water temp at the selected temperature - so there was no need to turn the tap down to get hot water.
Neighbours Combi (old design of Valiant - not sure of spec)
General impression - crude How water flow - slow Showers - unusable (water temp switches between warm and unheated) Baths - very slow
Unless you're meaning two bathrooms, a decent storage system with a fast recovery cylinder should be capable of re-heating the cylinder in the time most would take to have a bath. If there is a regular need for two baths at the same time, I'd say you need a larger than normal storage system.
I went from the old fashion storage with a header tank to Combi.
I gain the area used by the Hot Water Tank (I have a smal semi) and lost the problomatic cold water header tank in the attic
Very rarely use the bath, rather an electric shower, and pay one bill for all energy used.
I did install from scratch a Combi that got round my main Combi complaint in a flat of mine, the complaint is the wait for the hot water to the Kitchen sink from the far away Combi. (In the flat I sited the Combi beside the sink). I guess the installation using existing Stored water pipes was not the correct thing to do, but we all know the pressure of making a buck.
I cannot help but wonder at modern Combis being sited miles from the target tap. A new house has the boiler sited in the Garage. Bloody Regs, I bet.
I'd like to know what's 'problematic' about a tank with a ball valve? It's yonks old technology and should work perfectly for many years with absolutely no attention.
Well, if you don't use a bath and you're happy with an electric shower, so be it.
No - this is a DIY group and most would be advised to design for requirements - not making a fast buck.
Since there will be several hot 'taps' in the average house, it's not possible to have the water heater or store close to all of them.
Earlier today I tried to find a post a did a few year ago both relevant to this topic.
1) Contained a list with a couple of dozen criteria which might need to be considered when choosing a heating system. Needless to say the matter of combi v. stored was addressed therein.
There is no "one size fits all". Why some people should find this such an unattractive idea I can only make wild speculations.
The other post I found...
To parody Fowler on the subject of split infinitives:
The combi questioner can be divided in several groups.
Firstly, those who neither know nor care. These are the happiest of all especially if someone else pays the bills.
Secondly, those who don't know and do care. They post to uk.d-i-y.
Thirdly, those who know and always approve. We all know who they are.
Fourthly those who know and always condemn. To those of you who are in this group I beg you to read on. I suspect that this group is larger than it might otherwise be on account of two factors. Firstly there are a proportion of professional installers who for their own reasons prefer to always fit a combi regardless of the needs of the customer. Secondly those in the third group whose style of advocacy could be described as abrasive.
Fifthly those who know and discriminate. There are quite a number of criteria which have to be considered. User's informed preferences. User's previous experience. User's prejudice. Size of dwelling: Space v. cylinder benefits. User's HW usage patterns. Instant Availability v. Storage heat losses. Number and size of simultaneous or back-to-back HW demands (Showers v. baths.) Quality of mains supply. Pre-Existing arrangements, cost and upheaval implications. ...
I've found combi's acceptable for baths and bathroom sinks (flow rate OK, temperature just about OK if throttled correctly) but in the kitchen you need somewhat hotter water particularly for "spicing up" a sink of dishes which has started to cool off. I used to use a kettle but have now put one of the Screwfix electric tank heaters under the sink, on a second tap. Perhaps not the greenest solution but very convenient.
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