Getting rid of water tank in loft.

[mick2me 3,033]

When this house was built there was low water pressure, therefore two large tanks were installed in the loft as a reservoir,

Since then the pressure has increased. I would like to get rid of these two tanks.

Is it a matter of bypassing the tank feed? Anyone done this?

[benjamin1945 16,248]

I let the mrs deal with them sort of things

[Ayupmeducks 1,730]

Unless things have changed, which they probably have, it used to be that a hot water system had to be low pressure Mick, with a cold water tank in the roof to supply the hot water heater/back boiler etc.

We use full mains pressure over here on the hot water tank, but they have protection such as, high pressure relief valve/overheat valve.

UK systems didn't have those protections and relied on the cold water low pressure tank as that same protection.

I'd seek advice from a plumber Mick.

[colly0410 1,183]

Our system (house built in late 70's) is: cold water = high pressure straight off mains to all cold taps & both toilets. Hot water = low pressure storage tank heated by gas central heating boiler to all hot taps. Asked my plumber/gas fitter mate about updating to a new system, he said "if it's working OK leave it alone!" He said high pressure hot water systems OK till they go wrong, so I'm keeping the old system going as long as possible..

[Ayupmeducks 1,730]

Ahh so they have changed then Steve.

As far as just hot water mains pressure for showers etc is concerned, I've never had any problems, either here or Australia.

[Bilboro-lad 294]

You need a combi boiler, then you can get rid of the tanks.

[darkazana 1,736]

Not all tanks will come out of a loft, even though they went in! We had a combi boiler installed in our last house but they couldn't get the old tank out of the loft. They think it must have been put in before the ceiling was put up, it was definitely too big to get through the hatch.

[NewBasfordlad 3,599]

Mick what boiler have you got. And do you have a hot water cylinder?

All redundant tanks will come out the loft that's why you have a disc cutter.

If anyone has changed from a conventional low pressure system to either a combi or a unvented cylinder don't forget to check whether your insurance company will give you a rebate for not having tanks in the loft.

[The Engineer 614]

Mick,

Removal of the tanks depends how they are connected. You say two tanks - are they similar size? If so they could be one for hot and one for cold - alternatively they could be combined (maybe a double size tank was not available or there was a need to spread the weight - 1kg per litre).

In UK, "traditional" (meaning old) systems connect cold water "mains" to toilets, electric shower and all cold taps (bath tap might be exception - see below). Hot water systems that employ a storage tank (usually a lagged copper cylinder in the airing cupboard) often has parts that cannot withstand mains pressure (in particular the copper cylinder). The low pressure comes from the header tank, which has to be large enough to replace the cylinder-full of hot water without running dry. The tank is "vented" (contrast with "sealed" system though don't confuse covered with sealed), meaning that the pressure is purely atmospheric and is proportional to "head" (hence tank goes in loft).

The copper cylinder is typically "indirect" - one lot of water flows from the header tank, into the bottom of the cylinder, gets heated (by primary water or immersion heater), rises to the top, flows to the hots taps. This is called the "secondary" circuit. The "primary" water circuit circulates between the boiler and a coiled tube inside the cylinder; heat is transferred from primary to secondary. The old type of boiler cannot withstand high pressure so the primary circuit also has a tank in the loft to provide pressure/head. This is called an F&E (feed and expansion) tank and is usually quite small (something like a 15" cube). The primary water also flows around the radiators and has corrosion inhibitors (radiators being steel).

In this system, the bath cold tap can be (ought to be) connected to the output of the header tank so that it has the same pressure as the bath hot tap - this is important where there is a mixer tap, often with a shower function.

If the incoming mains is low pressure, the toilets (and header tank) would probably be fitted with low-pressure inlet nozzles to let the water in at a reasonable rate.

Along came combination boilers which simplify matters through instant heating of the hot water - no external storage is required. Combis are designed to withstand the higher pressures and have various built-in safety systems - hence they are not cheap. They are called combination because they have two circuits - one for central heating and one for instant hot water. The circuit for central heating is pressurised (though not as high as cold water mains pressure) by admitting water to it through a removable linking pipe/hose. There's a pressure gauge (typically a couple of Bar but must be charged to be in range specified by manufacturer) - if pressure drops too much (e.g. through a leak or excessive radiator bleeding), the boiler will shut down.

Lastly, if your hot water demands are higher (e.g. big house with bathroom and one or more en-suites), a combi boiler will not have the capacity to heat enough volume quickly. The solution is a high pressure sealed hot water system.. This goes back to a storage cylinder but now it can withstand high pressure. There are a couple of expansion vessels but no header tanks. This has the makings of a giant boiling-water bomb (can demolish a house) so it has to be installed and maintained correctly.

So, can you just bypass a header tank? Maybe, maybe not. If you can trace out the pipework, that would be a start.

Engineer

[mick2me 3,033]

The heating is original Glow-worm Majorca back boiler, works perfectly.

British Gas just quoted me £4,000 to Install a Combi to existing radiators.

It appears to be fed from a small seperate tank in the loft.

Kitchen tap is mains cold all other cold taps come from the tanks.

I just want to feed those taps and cylinder (immersion heater) with mains.

[mick2me 3,033]

Thanks Engineer, I will see what I can do.

I had thought it would still need a header tank for the copper cylinder, whist also heated by the back boiler.

[NewBasfordlad 3,599]

Hi Mick conventional low pressure system.

First no you cannot feed your hot water cylinder with mains pressure well you can but you will blow it up and flood your house.

The taps can be changed to high pressure. First you will need to check your cold water storage tanks in the loft. what you are looking for is the pipe from the bottom of one of the tanks that feeds the cold circuit not I repeat not the hot water cylinder. The easiest way to effect a conversation would be to cut this pipe as it leaves the tank (Don't forget to drain the tanks first) and cap the stub from the tank. Cut into the rising main that feeds the ball valve to the tank and tee into this, run your new pipe and connect on to the pipe that feeds the taps. If your WC is fed by low pressure you will have to fit a new high pressure ball valve.

[NewBasfordlad 3,599]

As to £4k to fit a new combi don't BG make you howl with laughter. My man is doing one for me this week.

Old boiler and cylinder out, re-pipe 3 rads, fit TRV's to all but one radiator which is in the reference area, new Baxi Dou-Tec 28 HE a combi with 7 year guarantee, programmable room thermostat, fully compliant with Building regs £2350 total cost.

[colly0410 1,183]

My plumber/gas fitter mate was telling me a about a newish system called a 'thermal store', it has a tank of hot water at low pressure & mains pressure water goes through a heat exchanger coil in the tank, so you've got mains pressure hot water at the taps with a high flow rate. What the advantages of it are I don't now..

[NewBasfordlad 3,599]

They have been around a few years now and have much improved over the first offerings which were dire. Problem is they are damned expensive if they go wrong.

If you are wanting high pressure hot water and have a gas supply then a combi is the way to go. Cheap to run and now with sizes up to 42Kw and preheats they can cope with most domestic dwellings. Only downside is they are expensive to repair so always get one with a good guarantee.

If you are on benefits and your boiler is older than 7 years there is a good chance you can get a brand new boiler for free.

[The Engineer 614]

Thanks Engineer, I will see what I can do.

I had thought it would still need a header tank for the copper cylinder, whist also heated by the back boiler.

Mick,

That's right - the back boiler isn't designed to take high pressure so is fed from a header tank (it's a vented system). However, the water passing through the back boiler is "primary" and will flow through a heat exchanger (coiled tube) in your copper tank to pass the heat to the water that comes out of hot taps ("secondary" circuit) then back to the boiler. There's likely to be some arrangement of pump and diverter valve as well if you have CH. The header tank for the primary circuit / back boiler is usually a small "feed and expansion" variety. Have a look at your copper tank - pipe at top = hot water out, pipe at bottom = cold water in (from big header tank), two pipes on the side = flow and return from the boiler (primary).

[mick2me 3,033]

Yes that is the arrangement for hot water.

First thing I did was to do away with the stat (in the hall which we rarely heat) and replace the controller with a Wireless system for water and heating.

The intention to move the stat from lounge to bedroom.

There is a wireless stat in contact with the tank, but this system reqwuires the HW to be on or the CH cuts out. Therefore I had to take the tank stat off, or once up to temperature it cut off both HW and CH?

Also it appears that the upstairs rads work off the HW system somehow? If we have it on at nighh it gets very hot?

[NewBasfordlad 3,599]

It was usual at one time to take the bathroom radiator of the primary circulation pipes. But by the time your back boiler was fitted this practice would have been redundant. It would sound to me as if you are suffering from gravity circulation on the upstairs radiators which would not be unusual in a system of its age. You could cut a one way valve in the system but without making a survey I could not tell you where to site it. Another cure would be to fit TRV's on to the effected radiators. The problem with moving the room stat to a bedroom would be that in this case it would cut the system off prematurely leaving you cold downstairs.

Having said all that I think you have just moved there Mick in which case you wont be leaving soon, it may well that the time has come to bite the bullet and get things sorted.

The old Baxi either a 45 or 55 back boiler unit (Majorca is just the fire) is a band 'G' boiler and only about 60 odd per cent efficient where as a new band 'A' condensing boiler is more like 90% so a good saving over the life of the boiler.

Another problem you going to face is the availability of spares, gas valves (24 volt) for some of the older Baxi's are already unavailable. I always believe it is better to do a planned exchange rather than a forced job because you have no heat or hot water. That way you get time to get yourself up to speed with what's on the market, obtain different quotes etc. And most important you won't be in the hands of some bar steward who ups the price because he knows the lady wife is giving you earache to get the job fixed.

[mick2me 3,033]

When I saw the price come up on the BG mans laptop I laughed and said if its more efficient, how long is it going to take me to recover £4000 replacing a boiler that is in perfect working order, by what I gain in increased efficiency?

He then gave me the same, about unavailability of parts, and the frightener, "if it breaks down it will be in the winter, leaving you with no heating or hot water!"

a. it has continued to work without problems since 1977, how long before I have to replace a combi.

b. we wont be without heating or water, there is a gas fire, we can plug in electric heaters, we have an immersion heater,

I will scan the quote they gave me itemising each part of the job. The boiler is quoted about £1100, but recon BG buy so many they probably get it much cheaper. I guess they are charging me £3500 for fitting!

[NewBasfordlad 3,599]

The main problem with BG and the prices they have to charge is really quite simple.

BG don't have any engineers capable of installing boilers or heating system therefore they have to use subcontractors plus they have sales personnel. Now I have no idea how much sales people are paid now but back in the 80s Servowarm (remember them) were paying just over £100 for every boiler swap sold.

The other thing to ask is what make of boiler are they installing answer usually their own brand. They trade now on the reputation earned by the original gas boards and you would be surprised how many people fall for it.

As to boiler life expectancy that has decreased as the have got ever more technical. Now according to Which magazine you can expect about 10 years during which time you spend another £1000 in repairs before it goes beyond economical repair.

The problem you face is that when you do have to change your boiler you will have no choice but to fit a band 'A' condensing type.