I have noticed a damp patch on the wall in the hallway downstairs, it has been getting gradually larger over the last few days. I suspect it is coming from the hot water cylinder which is located directly above this wall. I have had a quick look and cannot see that it is leaking from any of the nearby pipes so I suspect the leak may be from the tank itself. Is replacing the cylinder something that can be DIY'd without too much trouble ? Any advice or pointers which might help ? It is an indirect system with the cold water tank directly above in the loft.
While I may be forced into replacing the hot water cylinder, it gives me the opportunity to bring forward one of those jobs which I have been considering. That is to move the cylinder up into the loft. I realise I will have to replace the HW cylinder and CW tank with a combination unit but are there any drawback to this that I need to consider ?
The cold water section of the combination cylinder may not be big enough to supply both hot and cold water, depending on which model you buy. The cold section is designed to feed only the hot water in kost models. You can get
50-50 splits in combination units of 115 litres each. Then the cold water supplying the bath can be taken off the tank also. You may have to cut out a hole in the bottom of the cold water section and fit a tank connector for the cold feed to the bath and basins. It is best to have a 22mm cold water mains feed to the combination and fit a Torbeck ballcock which is either open or closed, especially if you have an 80 litre cold section. The Torbeck is silent fill. These are 1/2" connection, so it may be better to fit two of them to get the fast fillup. If an 80 litre cold tank section, then it acts as a break tank leaving the combination unit on low and safe atmospheric pressure, unlike an unvented cylinder.
The problems is having high pressure showers. This can be achieved by having a combi do only the shower. The CH side can be as a normal boiler. or, a power shower pump, or a venturi shower.
Get a quick recovery coil in the combination cylinder/tank.
If the mains are good flow and pressure, a minimum 22-25 litres/min, then consider a mains fed Pandora Heat bank. This can go in the loft and needs no header tanks or overflow. All the house will then be at mains pressure. Easy to DIY. Unvented cylinders require a BBA approved installer, heat banks do not.
If installing in a loft, install a mains pressure system. You need to check that your mains flow rate is good enough first, but a mains pressure system solves the problem of needing lots of cold water storage above the hot water cylinder. It also gives mains pressure hot water to the taps and superlative shower performance. They also typically have higher bath filling rates. I even use mine with a hosepipe to wash the car with a foaming hot brush.
I have a DPS Pandora heatbank in my loft, which works very well and is easy to install if you are happy doing pipework. You could also install an unvented cylinder. For advantages and disadvantages of both, google groups is your friend. The differences have been done to death in the past, but I suspect the heatbank is likely to be better for you.
I'm fairly sure that the cold water feed in the bathroom already comes from the mains. Can't be 100% positive but I seem to recall that last time I turned the water off at the stopcock the bathroom supply dried up pretty much immediately. I'll double check when I get time. If this is the case then the CW tank will only be there as a feed for the HW Cylinder so in a combination cylinder is the size of the CW part important ?
Yes, if you fill the bath quicker than the combination tank fills up. The header tank will be much smaller than the bath capacity.
By all means fit a replacement gravity system if you want to save cash, but a mains pressure system is vastly better and weighs less, too, which can be a factor when installing in a loft with 3 inch joists.
Not so. The average bath is 100 litres and that is mixed hot and cold, so 80 litres of hot is about average. The average cold section on a combination unit is, eh presto...80 litres. Also as water is being drawn off it is being filled by the mains, so the cold section will not dry up. Fit a Torbeck valve which is either on or off, in place of the brass ballcock and it is highly unlikely you will run out of water in the cold section. Fit a
22mm mains pipe to it and two Torbecks and you will not run it of water in the cold section. Fit a quick recovery coil that takes all the boilers output, and a priority system on the heating system and you will never run out of hot water in normal use.
If a venturi high pressure shower mixer is also used (no power shower pump needed) then using a combination unit is a cheaper and better alternative to a heat bank or unvented cylinder. Low pressure water storage, cheaper, simple solution, no: complexity, elecricity needed, large bore blow-offs, self venting if mains failure, about the same size as an unvented cylidner or heat bank for equiv performance, and the same overall performance.
If you want a fully sealed system so that the loft space has no water open to atmosphere up there, then unvented cylinders or sealed heat banks is the way.
is an example. All are lagged; both the hot and cold sections. Combination units can be made to order, say: 115 litres in each section, high insulation values, quick recovery coil and a cold feed connection on the bottom of the cold section. Using the cold section for both hot and cold feeds, then it would be advisable to have a 22mm mains pipe to the unit (if possible) and two Torbecks fitted to ensure maximum re-fill (the unit may be filling faster than what is being drawn off at times, depending on the incoming mains flow.
"Christian McArdle" wrote in news:40c73291$0$20517$ snipped-for-privacy@reading.news.pipex.net:
What's this "lighter" Christian?
I admit I haven't done any homework, but as you appear to be knowledgable, I might as well just ask!
My impression on just looking a t them, was that you would have to store a lot of water at a high temperature to get the heatbank effect, and they certainly *look* massive.
Was that wrong? (I'm still making up my mind on my own replacement)
The heatbank stores water hotter, so stores more energy and could be slightly smaller for the same performance. It doesn't have a cold tank on top of it, which weighs loads.
Christian, I don't think I fully understood your point yesterday but having spent a little time I now think I understand.
The idea of having hot water at mains pressure does appeal, especially as I am planning on installing two new showers in the house over the next few months, however I had never intended replacing the existing cylinder and I am being forced into considering my options due to an apparent leak.
The point is, cost is an issue for me as is speed of installation, I am hoping to be able to do everything over the coming weekend and still have hot water by Sunday evening (and without missing the England game). The option of moving everything up into the loft is something I had been considering as part of my future plans to help increase space in the smallest bedroom. I am fairly keen that the existing central heating system is still used to actually heat the hot water regardless of the type of cylinder it is stored in.
If I was to choose an indirect combination cylinder as I originally planned then I believe the job would just involve redirecting some of the existing pipework. Is there any additional installation required if I go for the heat-bank system as suggested by Christian ? It isn't clear to me whether there is additional wiring needed for this.
Also can anyone give me comparitive costs, my existing HW cylinder is one of the smaller ones, I believe it holds around 90 litres. I was planning on replacing it with something of a similar or slightly larger size.
The standard Pandoras go from 130 litres to 415 litres. They also store more energy than a same size conventional tank. They also don't have 80 litres+ cold water to weigh down the joists.
A 250 litre Pandora will run 2 baths (possibly 3) simultaneously no problem. A 125/125 combination will run only one.
I never even get close to running out on a 180L model, but I oversized it as I expect to install a second bathroom at some point.
If you are DIYing, you had better figure it all out first and ensure you haveall the materials. Frequent trips to B&Q eat up weekend time. Put aside a "full" 10-12 day weekend to do it. Look at
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Look at the Pandora. The Pandora is easy to fit. You need a power supply to it. The Pandora takes 2-3 weeks for delivery.
The combination cylinder is easy to fit and requires just extending your pipework and needs no electrical connection. The showers? Use venturi showers, that give high mains pressure and no pump. If you have a pump, then when you come replace your boiler, fit a combi and run only the showers off it and have the CH side operate as a normal boiler heating the CH and DHW, then no pump.
The heatbank is plumbed in exactly the same as a combination cylinder, except for the following differences:
You need electrical power for the pump.
The cold mains feed goes to an outside tap with hose attached, rather than to a ballcock valve.
No overflow is needed.
Basically, you have cold mains in, hot water out, flow and return to the boiler and that's it. Other things, like cylinder thermostats and zone valves are the same for both types.
It is actually easier to install than the combi, as electrical power is probably easier to source than an effective overflow.
The main problem is the cost, which is much more than a combination cylinder. However, against that is the fact that the showers can use simple cheap thermostatic mixers and don't need noisy, expensive or unreliable pumps.
An Albion 1200x450 Indirect Combi goes for around 250 quid. This has 115L hot and 40L cold storage. (No sign of the 80L standard according to IMM).
My 180L DPS Pandora cost 750 quid, although I could probably have beaten them down a bit if I had any negotiating skills. Obviously a 180L heatbank will annihilate a 115L gravity cylinder in every respect, but it is definitely the more expensive option, although it compares favourably with an unvented cylinder, especially when installation costs are considered.
If you look at the real cost of ownership, the difference isn't so clear. You should consider:
The fact that a copper cylinder with constantly fresh water will last a fraction of the lifetime of a heatbank filled with corrosion inhibited water.
You don't need expensive, noisy, unreliable pumps if you want a shower. (Gravity showers are fine if your idea of a shower is a dripping tap).
Filling is manual, so a leak (except in the mains pressure feeds, of cour se) doesn't result in an unlimited discharge of water. They also do automatic fill versions if you don't care about this possibility.
If the heat exchanger does scale up, it is simple to descale without replacing the entire cylinder.
You'll need to be quick if you want it installed by Sunday, though. Although I understand that DPS now hold stock of popular items, delivery in such a timescale might be problematic.
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