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Yellow Fang
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That would be brilliant.
Replacement for a hot water cylinder
- Thread starter Yellow Fang
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That would be brilliant.
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Yellow Fang
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I've been reading up about water heating in the library, in particular, Kells and Faber Heating and Air Conditioning in Buildings.
Things seem a little clearer. Vented systems seem to be those in which cold water is fed in from a cold water tank in the loft, while unvented systems have cold water pumped in from the mains supply. Direct systems are those in which the water is heated directly by the heating element, like a kettle, and are regarded as obsolete because they're vulnerable to limescale build up in hard water areas. Indirect systems are those in which the heating system heats water in an enclosed in a loop of copper pipe which coils through your water tank where it loses its heat to the water that comes out of your tap.
I think it also explained some strange things about my old immersion heater, such as why the cold water pipe seemed to enter at the top of the tank while the hot water seemed to come out the middle, and what that extra pipe in which nothing flowed was doing. I am betting that there is a cistern at the top of the tank in which cold water is fed. The cold water feeds down the side of the tank and enters the hot water tank at the bottom. The other pipe allows air to enter the cold water cistern to equalise the pressure. I guess this also explains why there is no insulation on the top or the bottom of the tank.
I seem to remember when I looked at getting gas water heating before that there was a requirement to put in a flue gas vent. I doubt this is a massive problem in my flat because it's solid wall, but wouldn't it be a problem in buildings with cavity walls? Couldn't it also lead to air-tightness and cold bridging issues (not that that's a consideration in my flat)? Wouldn't installing a vent also put up the expense?
A smallish, dual immersion heater water cylinder with lots of insulation seems like a cheaper and easier option, but I still suspect that a lot of the time I would be heating up water that cooled down again before I used it.
How do people usually control their immersions heaters? Do they leave them on all the time? My old water cylinder just had one immersion heater. I put a timer on the electricity plug to switch it one for an hour before 7am to use economy 7 electricity, then for an hour at about 7pm and 30 mins about 11pm. The dual immersion heater cylinders seems to imply the electricity should be left on all the time.
I picked up a brochure in a local renewable/economical heating systems shop, but they said they only supply commercial buildings - wtf? It's not what their brochures imply. However, like nearly every brochure I've seen, their domestic heating systems always seem to target nuclear families in modern, detached houses, in which a space heating is also assumed.
Things seem a little clearer. Vented systems seem to be those in which cold water is fed in from a cold water tank in the loft, while unvented systems have cold water pumped in from the mains supply. Direct systems are those in which the water is heated directly by the heating element, like a kettle, and are regarded as obsolete because they're vulnerable to limescale build up in hard water areas. Indirect systems are those in which the heating system heats water in an enclosed in a loop of copper pipe which coils through your water tank where it loses its heat to the water that comes out of your tap.
I think it also explained some strange things about my old immersion heater, such as why the cold water pipe seemed to enter at the top of the tank while the hot water seemed to come out the middle, and what that extra pipe in which nothing flowed was doing. I am betting that there is a cistern at the top of the tank in which cold water is fed. The cold water feeds down the side of the tank and enters the hot water tank at the bottom. The other pipe allows air to enter the cold water cistern to equalise the pressure. I guess this also explains why there is no insulation on the top or the bottom of the tank.
I seem to remember when I looked at getting gas water heating before that there was a requirement to put in a flue gas vent. I doubt this is a massive problem in my flat because it's solid wall, but wouldn't it be a problem in buildings with cavity walls? Couldn't it also lead to air-tightness and cold bridging issues (not that that's a consideration in my flat)? Wouldn't installing a vent also put up the expense?
A smallish, dual immersion heater water cylinder with lots of insulation seems like a cheaper and easier option, but I still suspect that a lot of the time I would be heating up water that cooled down again before I used it.
How do people usually control their immersions heaters? Do they leave them on all the time? My old water cylinder just had one immersion heater. I put a timer on the electricity plug to switch it one for an hour before 7am to use economy 7 electricity, then for an hour at about 7pm and 30 mins about 11pm. The dual immersion heater cylinders seems to imply the electricity should be left on all the time.
I picked up a brochure in a local renewable/economical heating systems shop, but they said they only supply commercial buildings - wtf? It's not what their brochures imply. However, like nearly every brochure I've seen, their domestic heating systems always seem to target nuclear families in modern, detached houses, in which a space heating is also assumed.
Chromatic
Legendary Member
- Location
- Gloucestershire
If all you want is hot water every now and then, then Andy_R has already given you the answer.
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Yellow Fang
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Andy R's answer is a good one. I am giving it some serious consideration. It mainly depends on cost, although I'm a bit concerned about reliability and maintenance.
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Yellow Fang
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It looks like definitions aren't consistent for boilers. Combi boilers sometimes describe combined space and hot water systems sometimes, or just hot water systems other times. A combi boiler without the space heating systems is just a condensing boiler, isn't it. A multi-point boiler is sometimes a boiler that can have more than one outlet, or a boiler that only has one outlet. If it's gas, multipoint seems to mean it can supply more than one outlet; if it's electric, multipoint seems to mean you need a separate unit for each hot water tap. Total crap!
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Yellow Fang
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Just had my mother on the blower. She says her combi boiler is costing her about £250 a year in maintenance. She said it worked ok for the first two years when it was under warranty and failed about a week later, and has proven unreliable thereafter. She said that whenever she phoned someone to fix it, typical story, he wouldn't turn up when he said he would. So she entered a contract with British Gas because they were the only organisation who would send someone promptly when it broke down. She says she spoke to my uncle who wasn't that impressed with instantaneous water heaters neither, because in his experience they were either scalding hot or only luke warm. They both reckon I'd be better off just replacing my copper water cylinder with another one.
Archie_tect
De Skieven Architek... aka Penfold + Horace
- Location
- Northumberland
You need some reliable advice - have a look at websites for Worcester and Baxi balanced flue condensing hot water heaters/combis.... + Gledhill hot water cylinders. If you decide to simply replace your cylinder you need to look at a like for like replacement, could probably get away with a 14 litre hot water tank but to fill a bath you probably need a 210 litre size...+ integral cold feed expension/supply tank, but get one with a minimum of 60mm foam insulation- using 2 immersion heaters, one on Economy 7 or equivalent and the other a 1 hour max. top up for 'emergency' hot water.
+ insulate all pipework to prevent heat loss from the pipework.
Your mother would be better getting a registered plumber to do the inspection of her boiler... shouldn't need £250/year maintenance contract!
Edit: 140 litre!!!
+ insulate all pipework to prevent heat loss from the pipework.
Your mother would be better getting a registered plumber to do the inspection of her boiler... shouldn't need £250/year maintenance contract!
Edit: 140 litre!!!
asterix
Comrade Member
- Location
- Limoges or York
"Your mother would be better getting a registered plumber to do the inspection of her boiler... shouldn't need £250/year maintenance contract!"
Do what you want but..
D-o-n'-t G-o N-e-a-r B-r-i-t-i-s-h G-a-s.
(and WRT scalding water, it is possible to get thermostatic taps. We have one for the bath that works excellently.
Do what you want but..
D-o-n'-t G-o N-e-a-r B-r-i-t-i-s-h G-a-s.
(and WRT scalding water, it is possible to get thermostatic taps. We have one for the bath that works excellently.
Chromatic
Legendary Member
- Location
- Gloucestershire
Our combi boiler has so far given about 7 yrs trouble free operation. I have spent £0 on maintenance and £0 on repairs in that time.
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Yellow Fang
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Interesting, Baxi have a micro CHP product and Worcester-Bosch are developing one. Also, interesting are Baxi's back boiler, which fit behind an electric fire in the fireplace. It would mean taking out the gas fire, but it's tatty and I rarely use it anyway.
Anyway, thanks for all your views.
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Yellow Fang
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[QUOTE 1540199"]
I got a Which magazine through the post yesterday. They advise to avoid Baxi. Worcester came out top with another which I can't remember.
[/quote]
Which magazine, is that worth subscribing to?
I got a Which magazine through the post yesterday. They advise to avoid Baxi. Worcester came out top with another which I can't remember.
[/quote]
Which magazine, is that worth subscribing to?
asterix
Comrade Member
- Location
- Limoges or York
That's very much in the spirit of 'Which?'
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Yellow Fang
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Seems a crazy way to run a magazine to me, but I have subscribed.
Apparently, the Building Research Establishment have found that condensing boilers are now no longer any less reliable than conventional gas boilers
Another consideration is that condensing boilers require an extra drain pipe to expel the condensate, which is slightly acidic. I suspect this means the boiler would have to go in my kitchen because that's the side of the flat where all the drain pipes are. I'm four floors up so how would they attach another drain to the down pipe - a cherry picker perhaps? I can see how this could get expensive.
Also, even the cheap condensing boilers on their own do not look all that cheap when compared with immersion heaters.
I wonder if those back boilers I saw on the Baxi website that go in the fire place are actually condensing. Traditional masonry chimneys can't be used as a flue according to wikipedia because the exhaust gases are not buoyant enough.
Apparently, the Building Research Establishment have found that condensing boilers are now no longer any less reliable than conventional gas boilers
Another consideration is that condensing boilers require an extra drain pipe to expel the condensate, which is slightly acidic. I suspect this means the boiler would have to go in my kitchen because that's the side of the flat where all the drain pipes are. I'm four floors up so how would they attach another drain to the down pipe - a cherry picker perhaps? I can see how this could get expensive.
Also, even the cheap condensing boilers on their own do not look all that cheap when compared with immersion heaters.
I wonder if those back boilers I saw on the Baxi website that go in the fire place are actually condensing. Traditional masonry chimneys can't be used as a flue according to wikipedia because the exhaust gases are not buoyant enough.
swee'pea99
Squire
Another thumbs up for Worcester Bosch. I actually wanted a Valliant - I'd always been led to believe they were 'the best' (sort of like Miele washing machines). But the bloke who fitted it said WB were more reliable with London water. Sounded like BS, but what do I know? He fitted it and it ran faultlessly for six or seven years with no maintenance. Then some sort of expansion thingy went wrong, so that needed replacing, so that was a hundred quid or something. Since when, again, no problems at all. It must be eight years now?
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Yellow Fang
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I was talking to a friend who said he'd spoken to several heating engineers about condensing boilers. Apparently the improved efficiency is often not as good as anticipated because they're very hard to set up right. Reading around, it seems that this is partly because most existing radiator systems need water temperatures about 80 degrees, so not an awful lot of the water vapour in the exhaust gases actually condenses. They would probably work better with lower temperature heating systems, such as under floor heating or larger radiators. If they were just used to heat tap water, the efficiency would be better because the water temperature does not have to be so high. I see why these boilers are usually combined space and water heating. By the time you've invested all the money in buying the boiler and getting it installed, it makes sense to invest that bit extra for the radiators. It's a classic rebound effect because after making that investment, you want to get your money's worth with the heating, especially as it's now so cheap and efficient. I reckon it was a mistake changing the law to insist all new boilers were condensing. They're more complex, harder to install, more expensive and have more to go wrong. Compare that with an electric immersion heater, which is nowhere near as complex or expensive to install, does not need as much maintenance, but is far less energy efficient.
