Confronting More Plumbing Phobias!

[Nigel Watts]

Now that I have nearly sorted out my Baconesque loo problem thanks to your help I am now feeling confident to tackle some more plumbing issues which I have long been putting off....

1. A year or two ago, when mending floorboards, I managed to nick a copper central heating pipe with my chisel, causing a small but troublesome leak. The pipe leads to a radiator in a room earmarked to become a bathroom one day but still in use as a store room. There happened to be an isolating tap in that same pipe run, so I turned it off, and it has stayed off ever since. Is there a solution which does not need soldering skills?

2. Hydraulic hammering is a regular occurance in the heating system, especially in the bedroom radiators. The system was completely replaced about five years ago but I guess it has got out of balance or something. Is this solvable by an ignorant amateur like me?

3. I have an old gas pipe under my living room floor leading to the fireplace, which used to have a coal-effect gas fire. I have long since replaced the grate with an antique one which burns coal and at the time I instructed the builder to disconnect the gas. A year or two ago I thought I would remove the now redundant gas pipe and tap at the bottom of the grate, which for some reason was still there. On starting to unscrew the joints I was met with a loud hissing sound and gas smell, so I rapidly screwed it back together again. The builder clearly had not followed my instructions to disconnect the supply. I regularly light coal fires in the grate, some six inches above the postion of the (live) gas tap. There have been no explosions so far but is this really safe? I guess fiddling about with live gas pipes is one for the pros?

4. I have an outside tap which is screwed on to a fitting at the end of a horizontal length of copper pipe. The only way to stop it dripping is to ensure it is tightly screwed on. This results in the tap being in a rather unconventional horizontal configuration which is both inconvenient and casues the wall to get damp. How can one get it to be both vertical and watertight?

Any solutions would be much appreciated!

 

[Cloudscape]

This sort of thing might mend the pipe in [1]: http://www.diy.com/diy/jsp/bq/nav/nav.jsp?forceStaticLeftNav=true&action=detail&fh_view=detail&fh_location=//catalog01/en_GB&fh_secondid=9271758 (a proper repair would mean cutting out the damaged section of the pipe)

Clean the pipe well first, with wire wool.

[3] Sounds pretty bad. The pipe needs capping off, well away from the fire.

 

[MdB]

[1] Use a pipe cutter to cut the pipe. I like this style:

Remove a suitable length section of pipe (measure lots of times - it needs to be fairly exact). Replace section of pipe with a solder coupling, a compression coupling, a plastic push fit or a brass push fit of your choice depending on the space available and your budget. The pushfits are very easy to use but are not cheap. The plastic versions normally can be removed but are fairly large, the brass push fits are smaller but can't be removed once fitted.

[2] Before doing anything else, bleed the system to get rid of any air. This may well cure it.

[3] GET THIS FIXED BEFORE USING YOUR FIRE AGAIN.

[4] PTFE tape is your friend... (start off with 10 turns)

 

[u102363]

[2] Do you have thermostatic radiator valves (the big knobs with numbers on)? If so, you can get noise as the last one or two close down as the rooms get up to temperature, if you do not have anywhere for the circulating water to go to. The usual solution is to have one radiator with ordinary tap type valves on it (often the bathroom), and just leave it on all the time. The newer solution is to fit an automatic bypass, whereby once the pipework after the pump gets up to a certain pressure it allows water to circulate straight back to the boiler.

I would try bleeding the system first. You get air in the highest parts of the system (usually the bedrooms) first if you have a small leak, or if you have no corrosion inhibitor in the system (the "air" is gases which are the by-products of your radiators rusting from the inside out).

You will know if your system is in need of balancing if some of your radiators take ages to get warm when the heating starts from cold. The solution is to partially close the valve at the opposite end of the radiators to the thermostatic or on/off knob, on the radiators which get hottest first. I find I usually need to close them fully then only open them again by about a quarter to half a turn. It's not rocket science!

Have fun,
O.

 

[Lime]

Water hammer in a boiler can be serious.
What kind of heating is it?

 

[Nigel Watts]

My house is on four and a half floors. The highest radiator in the house is in a bathroom tucked into the space at the top of the stairwell (the four-and-a-halfth floor). It doesnt have a thermostatic valve but most other rads in the house do. I regularly bleed this top radiator and ensure that the presurised system is topped up after doing so.

The boiler is a small, modern, balanced flue job in a cupboard on the ground floor. In the past it has made some funny noises and spurted water out of some nearby safety valves (at least that's what I think they are), but not recently. The main hammering comes from the bedroom radiators, usually when they are switched off or on very low, which reverbertes through most of the house. I have also experienced hammering in the living room radiators in similar circumstances. These all have thermostatic valves. Some radiators, such as those in the hall, landing and storeroom, are never switched on.

Silly question for obviously knowlegable people such as yourselves, but how does one go about draining a pressuried central heating system? In my old house a plumber insisted on doing this for me once, at a weekend, on premium rates, having made a small but urgent repair to a valve. He spent several hours apparently doing very little then stung me for the best part of seven hundred quid (now I think about it, I think that was about the time my plumbing phobia started).

 

[Penners]

1) I don't disagree with any of the solutions to your nicked pipe that have been made above. However, if it really is only a nick, you might get away with just a blob of solder on it. You'll need to make sure that the pipe is empty of water, and that you clean with wire wool (or scotchbrite) then 'boil' some flux on the surface first with your blowlamp. Then just allow a blob of liquid solder to fall on to the prepared surface.

However, don't do this if you feel that the 'nick' is large enough for the solder to end up inside the pipe. Use MdB's suggestion of cutting out and replacing the damaged section.

2. I once managed to stop pipe-knock by reducing the speed of my central heating pump. You should find a three-position switch on it - drop it down by one click and see. However, if this leaves you with some radiators not getting hot enough, you may have to wind it up again.

3. You need a corgi to sort this out - quickly.

4. Yes, generous windings of PTFE tape should sort this out - be sure to wind it around the thread in the opposite direction to the way you will screw the tap into its seat. i.e. viewed from the front of the tap, wind the tape anti-clockwise. But here's a tip - these taps always end up with the final tightening turn leaving them facing sideways or upwards - it's sod's law. So before you screw the tap in, pop a jubilee clip around the back of it. Then screw it in as tightly as you can, but stop at the last correct orientation before you reach the end of the thread. If you've been generous with the PTFE, the joint will still be dry, even though the thread isn't quite 100% tight. Then locate the clip so that it bridges the flanges on the tap and the seat, and tighten it up well. If the flanges vary in diameter, pack out the smaller one with a bit of rubber.

This technique has served me well with several garden taps.

 

[MdB]

Do you switch off your top radiator? If so, when the house gets to temperature, all the radiators are switch off and the pump has no way of circulating the water. The pressure goes up and you get all sorts of noises from the system. Solution is to either leave the top radiator permanently on or to fit a bypass valve.

If your top radiator is always left on then I don't know the issue and water coming from the safety relief doesn't sound good. An expert (that doesn't rip you off) may be needed.

 

[Nigel Watts]

One thing I forgot to add. On the first floor is a double cupboard which, on opening, looks like ICI's Billingham works on a clear day - two hot water tanks, a couple of spherical things, masses of pipes, switches, gagues, valves, pumps, lights etc. Noone ever thought to explain to me what all this does and it remains pretty mysterious (even though I did once succeed in obtaining a degree in Engineering from England's second oldest university). However in a spirit of curiosity I have tried fiddling with most of the knobs to see what would happen. One of these must have been the pump which Penners refers to. I think it was originally on the lowest out of a possible three levels. Turning it up to two made the hammering worse so it's back down at one again and I still get hammering.

In response to MdB - I think the top rad probably does get switched on and off. My teenage son who uses that bathroom is an eco fanatic and follows his parents around the house turning off lights and radiators and turning down thermostats. I will conduct an experiment to see if hammering is in any way correlated with whether that radiator is on or not. The safety relief problem may have happened when there was a lot of air in the system and the water pressure had fallen (does this make sense?). I have in recent times been monitoring regularly the pressure gague in the cupboard and topping up to 1.5 atmospheres (where a little red marker had been set, presumably indicating to me the correct level).

 

[chuckey]

I think that water hammer is caused by a rapid variation in the pressure of the water. This change in pressure causes pipes to bend then straighten repeatedly which causes more pressure variations and hence make the sound you actually hear. Hence the suggestion that is one rad was left on, the change in pressure would be smaller. Another would be to make sure that all the pipes are fixed properly (less bend, less noise). Another interesting idea is that the whole system is pressurised by a spring in the pressure vessel, so depending where it is in the circuit, it could be the spring in the pressure vessel, that is oscilating backwards and forwards (upwards and downwards?), causing the pressure fluctuations, and pipes to rattle. Or it could be a free volume of "air" in an unbled rad that is causing the oscilations. Not actually air, more likely to be hydrogen from a deficit of inhibitor in the system. Another point could be the DHW circuit and the divertor valve, if for some reason, the divertor was grinding about as it closed, so there was a change of pressure in the DCH system, which was rattling the pipes.
To mend your small leak, if you haven't a blow torch, get a jubilee clip that can be tightened down to the pipe size (15mm diam?), mark the pipe exactly 1" away from the hole. Bend a small piece of ali (copper would be better), say 1" square so it will go round the pipe, smother its inside surface with silicon goo. Get the pipe as dry as poss. Slide metal plate over hole, jubilee clip over metal plate( 1" away from your mark) and tighten. Wait 6 Hrs and see if you have fixed it.
Frank