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Tap! tap! is there anybody there?

Community Veteran
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Registered: 30-08-2007

Tap! tap! is there anybody there?

A number of times during my life I have needed to change a dripping tap washer, these have been exclusively cold taps, where the obvious turning off the mains supply has been pretty straight forward.
I now need to fit a new washer to a dripping hot bathroom tap (not the Supatap type) which is fed from a modern multi-point (water/central heating) heater. Is the procedure the same? does the heater need to be "primed" for use when the mains water is turned back on? or should everything work as normal straight away?
Whilst the water is off, I may take the opportunity to fit a couple of thermostatic radiator valves.
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
22 REPLIES
Lurker
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Re: Tap! tap! is there anybody there?

You don't say whether you have a stored hot water system, or an instantaneous.
The difference being that a stored hot water system has a separate recirculation system for hot water, in effect just having a radiator inside the hot water tank. (Actually a large coil, but you get the idea.)
If its this system, you should be able to turn off the feed out of the hot water cylinder, change the washer, turn on the feed again, and you are done. (With the advantage of minimal draining and bleeding. Wink )
If its an instantaneous system, the actual water that comes out of the tap is fed through the boiler.
In this case you could simply isolate the rising main, and approach in the same way you would for a cold tap.
You must of course pay attention to the boiler in this second case; The boiler must not be allowed to fire without water in it.
Many systems use an electric start to light a pilot, and subsequently the main burner. This is instead of the older permanent pilot light system.
If yours has electric start, simply isolate the electricity supply - this will prevent the boiler firing. (And the gas will have fail-off valve, so no gas can be released when there is no electric feed to allow the boiler to ignite, and monitor combustion)
If its a pilot light system, just turn off the gas supply to the boiler.
In either case, once you have tested and removed air, you can turn the boiler back on, and light the pilot if applicable.
Its not really much more complicated than a cold tap.
maranello
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Re: Tap! tap! is there anybody there?


Most multi-point water heaters I have seen are fitted with an isolation valve on the cold water inlet side. I have no experience of the older type, but I don't think they need to be primed as such, although it is a good idea to switch off the ignition system when you unisolate the inlet, and run the taps to remove any entrained air. The more modern systems which also provide central heating shouldn't be a problem, but you should bear in mind that the central heating and hot water systems are independant.
If fitting a thermostatic valve, I have always found pipe freezing sprays to be effective, but in pressurised central heating sytems it is always advisable to reduce the pressure by draining some water off via a drain valve, usually fitted on one of the downstairs radiator valves. You need to drain the radiator first as this takes time and the freezing spray  only works for so long. It is also a good idea to isolate all other radiators at both ends once you have reduced pressure in the system. Always make sure you have a fresh can of freezing spray if you are going to use this method.
Repressurising once you have fitted the TRV is done by opening the valve on the filling loop, which is usually a flexible pipe which connects via a T junction on the cold water inlet to the return leg of the central heating system.
The only other good advice I can give is, if you're not confident of what you're doing, get an expert to do it. 
My other car isn't a Ferrari
Community Veteran
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Re: Tap! tap! is there anybody there?

Thanks guy's; it is the instantaneous type (Volkera Maxin 24e) and it does have a pilot. It does have what I think is a pressure adjustment valve on a flexi-pipe, that I and engineers have adjusted the pressure gauge on the machine's facia, would this be the T junction/flexi pipe to which you refer Maranello? which obviously can be turned completely off if required, but can be a bit of a pig to reset afterwards, as its adjustment is quite fine. I would guess messing with this will continue to maintain the system pressure after turning off.
My inclination is leaning towards leaving to an expert.
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
pierre_pierre
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Registered: 30-07-2007

Re: Tap! tap! is there anybody there?

User Guide and service manual for boiler here http://www.vokera.co.uk/discontinued.asp
maranello
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Re: Tap! tap! is there anybody there?


The central heating part of the system should be a pressurised closed loop system. The pressure gauge reading will change depending on the temperature of the water. What can happen is that some corrosion may occur within the system which generates gas (hydrogen), or air is released from the water in the system. This can lead to cold spots near the top of radiators (usually upstairs), and the radiators have to be bled. This drops the system pressure as shown on the gauge, and normally this is restored by adding more water from the cold mains using the filling loop, the flexible pipe I was referring to earlier. I wouldn't expect this to be a fine adjustment, just open the valve until the pressure gauge reads whatever the engineer recommends, and then close the valve again. For most of the time this valve should be closed. If you have to leave it slightly open to maintain system pressure then it is likely you have a leak somewhere! There are usually two valves on the filling loop, the one nearest the cold supply is the one to open/close, the other end of the flexible pipe usually has a non-return valve fitted to prevent back contamination of the cold main.
My other car isn't a Ferrari
Community Veteran
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Registered: 30-08-2007

Re: Tap! tap! is there anybody there?

As always pierre, a mine of useful information.
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
Community Veteran
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Registered: 06-11-2007

Re: Tap! tap! is there anybody there?

Have you checked to see if you have a "scewdriver" controlled stop valve fitted in the pipe, just before the tap.... usually about a foot or so before it gets to the sink/bath ...... If you turn it to "across" the pipe, this should suffice for replacing the washer in the tap, without the need to turn off the mains, and of course, the boiler will not be "drawing water" so will not be switching on either !
(Just a thought! !)
looks like this >...................  http://i.ehow.com/images/GlobalPhoto/Articles/4840012/135835_Full.jpg
Community Veteran
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Registered: 30-08-2007

Re: Tap! tap! is there anybody there?

Yes thank you shutter, sadly there isn't one, that would have solved my problem very easily.
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
itsme
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Re: Tap! tap! is there anybody there?

Quote from: maranello

If fitting a thermostatic valve, I have always found pipe freezing sprays to be effective, but in pressurised central heating sytems it is always advisable to reduce the pressure by draining some water off via a drain valve, usually fitted on one of the downstairs radiator valves. You need to drain the radiator first as this takes time and the freezing spray  only works for so long. It is also a good idea to isolate all other radiators at both ends once you have reduced pressure in the system. Always make sure you have a fresh can of freezing spray if you are going to use this method.
Repressurising once you have fitted the TRV is done by opening the valve on the filling loop, which is usually a flexible pipe which connects via a T junction on the cold water inlet to the return leg of the central heating system.
The only other good advice I can give is, if you're not confident of what you're doing, get an expert to do it. 


The radiators that you are not going to work on I would advise to close both values so that you trap the water in the radiator and you will only be releasing/draining the water in the pipes. It's been many years since I did this myself but I believe that I did what I have suggested and also shutdown the lockshield value on the radiator that I was going to work on. I then released the pressure in the system by using the drain value on the boiler and then quickly replaced the value without draining the radiator. But I was not to perturb if I made a mess as I was decorating the room, so a bowl under the radiator and a towel wrapped around the pipe.
Community Veteran
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Registered: 30-08-2007

Re: Tap! tap! is there anybody there?

Well, locating the isolator at the boiler was eventually the easy part (it has got one) then it was off to Homebase for some washers. Do you know how many different types of tap washer there are? Do you know how difficult it is to find an assistant older than 16 years old in Homebase who can identify the correct washer when the right tap is pointed out, when there is no clue on the washer packaging? I have a headache from banging my head against a brick wall.
Its further away, but I'll try "The Depot" later on, I know its an off shoot of Homebase, but their assistants are often retired plumbers and engineers and more inclined to know what they're talking about.
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
Lurker
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Re: Tap! tap! is there anybody there?

Its a shame you don't have a hardware store about - I mean, you wouldn't go to PC World and expect to find computer experts would you?!?!
Seriously, I'd try an independant hardware store before trying one of the large retailers - at least the proprietor of such a business has a real interest in providing decent service.
Community Veteran
Posts: 7,154
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Registered: 30-08-2007

Re: Tap! tap! is there anybody there?

There was an "old fashioned" hardware store in Apsley, only a couple of hundred yards from Homebase, sadly it closed down a couple of years ago, having been put out of business by Homebase and a slightly closer Wicks. it was run by a couple of aging experts in everything, I could spend hours in there.
I take your point about PC World though James.
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
Community Veteran
Posts: 16,862
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Registered: 06-11-2007

Re: Tap! tap! is there anybody there?

Ok, so there your are, with the water turned off, got the tap in bits, and fixed the new washer.....  Smiley
Then you notice that the "seat" of the tap is a bit "rough".... Sad
fitting a new washer will stop a small leak for a while, but the water will find a way under it, and it will start to leak again, UNLESS you "re-seat" the tap....
so while you are at the DIY store, ask for (or find it yourself) a "tap reseating tool"...  (about £8-£10), but well worth it, even if it is just to "shine up" the old seating.... Cheesy
(same principle as valve grinding on a car engine)
Looks something like this.......  >>>>  http://ecx.images-amazon.com/images/I/417K3CEPRML._SL500_AA280_.jpg
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Re: Tap! tap! is there anybody there?

Plumbers merchants are the best place for that kind of stuff and they are usually a veritable mine of information especially round the trade counter as the info flows from both sides Smiley.
Speaking from personal experience as a once regular visitor to such trade counters.
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