Plumbing System

[tonyt]

I have a mains supplied only domestic plumbing system. There is no water tank in the loft and all taps, etc are supplied directly from the mains.

My boiler is a combi boiler.

The other day I turned off the water at the stopcock and turned off the boiler. I then ran both the upstairs and downstairs taps dry.

My task was to cut a pipe leading to a radiator and cap it off. I cut the pipe and water shot out right up to the roof. Luckily I managed to cap the pipe almost immediately so no harm was done.

I'm confused as to where the pressure in the system came from and, if it's there although the boiler is off, then how can I release it.

There are no draincocks anywhere in the system (it is sealed) and I cannot see any drainage device on/under the boiler.

Is there an easy way to drain a system like this?

Thanks,

TonyT

 

[Bahco]

You should have drainvalves on each of your downstairs drops if your system was fitted correctly
If not you will have to drain down via your downstairs rads. If you can work out which drops will drain the pipes you wish to work on it will be less work than a full drain down.
You will need to place a container such as a paint roller tray under the rad valve and unscrew SLOWLY until you get a small flow and then keep emptying this tray into a bucket with a scoop or cup etc.
Very painstaking and messy and do not envy you Add inhibitor, re-presurise boiler to 1 bar when you have completed your pipework, (you will need to cap off both pipes if you are completely removing a rad

 

[TexMex]

Don't most drain valves have a tail on them, so you can attach a hose and lead it out to the garden?

 

[ollski]

You should have drainvalves on each of your downstairs drops if your system was fitted correctly
If not you will have to drain down via your downstairs rads. If you can work out which drops will drain the pipes you wish to work on it will be less work than a full drain down.
You will need to place a container such as a paint roller tray under the rad valve and unscrew SLOWLY until you get a small flow and then keep emptying this tray into a bucket with a scoop or cup etc.
Very painstaking and messy and do not envy you Add inhibitor, re-presurise boiler to 1 bar when you have completed your pipework, (you will need to cap off both pipes if you are completely removing a rad

When you finish draining down I would buy a drain cock and fit it, or you will regret it next time!!

 

[breezer]

no one has mentioned your problem in the first place
I cut the pipe and water shot out right up to the roof.

as you said it is a sealed system, it is also pressuried to 1 -1.5 bar, so all though it was off its still pressureised

 

[ollski]

yes sorry, your heating and hot water are completely seperate and never mix, running your taps off is fine if you need to work on your hot water system, but will have no effect on the heating side.

 

[oilman]

If you have no drain cocks, you can relieve the pressure (probably done by now) by opening the pressure relief valve in the boiler. Don't listen to anyone who tells you shouldn't open the valve or it won't shut again. They should be tested every year, otherwise how do you know it's not stuck shut?

Once the pressure is zero, if the boiler is downstairs, you could use the pressure relief to drain the system. Just open the bleed vents on the radiators, upstairs first.

Another approach is to close off the valves to the particular radiator, put a container under the valve and open the radiator side connnection and drain the radiator. Then connect a pipe to one of the valves, and take the end outside, then open the valve. Remember to open a bleed valve somewhere to let air in.

You could also consider a pipe freezer.

 

[kevplumb]

just a thought guys but why not fit a drain to the part thats capped while its drained at least you can drain part of the system in future

 

[Bahco]

just a thought guys but why not fit a drain to the part thats capped while its drained at least you can drain part of the system in future

Good idea IF the capped pipework is downstairs, Why didn't I think of that

 

[PEDANTICVINDICTIVEMAN]

What a dipstick, thank goodness it wasn't a gas pipe, if you dont know what your doing leave it to the proffesionals.

 

[breezer]

What a dipstick, thank goodness it wasn't a gas pipe, if you dont know what your doing leave it to the proffesionals.

you cant say that on here , we must always give the answers to any questions no matter how dangerous, unqualified, cheapskate, for fun people are

 

[corgiman]

I find one of those self cutting washing machine taps well handy when you cannot find a drain off............. Just dont leave it on there

 

[oilman]

..........if you dont know what your doing leave it to the proffesionals.

I've seen work by amateurs who "knew nothing" and it was faultless. I've seen work by professionals that was ridden with faults.

This statement about professionals (note only 1 "f" required, and "your" should be "you're" (pedantic or vindictive?)) is usually made by second rate operators. Good operators remember how difficult (or not) they found things when they first tried it, and provide support, not deride peoples efforts.

The only difference is a professional gets paid for cocking it up, an amateur does it for free.

 

[PaulAH]

Sharpen up, Oilman.

Peoples? People's (possessive plural)

 

[kevplumb]

CHILL guys