Draining Central Heating System - I have a problem

[smittydj]

Hi,

I have used this forum many times in the past and got some great advice for my projects but never needed to post.

I am getting a lot of air in my radiators and i have to bleed the frequently. I cannot find any leaks where the air may come in from. I tread on a forum somewhere that a build up of sludge can cause gas to be created which causes the need to bleed and a good drain and refill (several times) followed by use of system restorer (X400) and inhibitor (X100) may solve the problem. I have the Sentinel products and wanted to get it sorted as i have to fit a towel radiator in my en-suite.

I have attempted to drain my oil fired central heating system (which should have been a reasonably easy job) but i am having trouble getting any water to come out when i open the drain valve.

I only have 1 drain valve which appears to come from the boiler, there are none on any of the radiators in the house. (I have attached 2 photos of this for you to see).

My questions are this,

1. is this the correct drain valve to use (as there is only one)?
2. Is it therefore blocked? (valve in good condition, opens easily)
3. If not, how do i go about draining it?

My system has a Worcester Danesmoor 20/25 oil boiler and there are 14 radiators on the system. It is not used to provide hot water. If any more info is need please ask.

I hope someone can help me with this?

Thanks in advance.

Dan.

 

[smittydj]

Upon closer inspection i have just found another drain valve on the oppposite side of the boiler, when turned this drains out some lovely black water so maybe this is my valve.

Is it ok to drain from here?

 

[Hugh Jaleak]

Should be ok to use any drain valve to empty the system, drain off should be fitted at all low points in the system to enable that area to be drained. (If the ground floor pipes run under the floor then sometimes only one drain off is needed or fitted.)

The drain off that wont work could be blocked or sometimes the washer sticks, opening the valve leaves the washer stuck to the seating. You would need to remove the spindle and retrieve the washer with a piece of wire or similar, but i'd try and get as much water as possible out first or you'll have an unholy mess to contend with.

Fit new washer before refitting the spindle and dont overtighten it when closing it!

 

[smittydj]

Thanks for that.

I took the plunge and started to drain it with the second valve - its working so thats a good start. Only problem is it is taking ages, only have a trickle coming out. Patience is a virtue!!!

Water coming out is very clean though - that will be the water from the downstairs rads first so not had trouble with them - will have to see what it is like when it comes from the upstairs rads.

Also, the small tank in the loft does not appear to be draining down, should this be the case? water is off at the mains.

 

[kbdiy]

If you're draining the whole system you will need to open the air vents on each of the rads to allow air into the system as the water drains out. Also the cold feed from the F&E tank may be blocked/sludged up and therefore the tank won't drain.

Try opening the rads first and see if the flow increases. Also bear in mind if there are any drops to rads without drain cocks, each drop will need draining individually.

 

[Hugh Jaleak]

Trickle may well indicate a stuck washer in the drain off, once you're confident it's stopped draining, may be wise to remove the gland/spindle totally and check/replace washer as necessary.

If the F&E tank isn't emptying then as said, could well have a blocked cold feed. Run a magnet along the pipework, if it attracts then that's a sign of a blockage.

May well find it's the last bit of water that comes out filthy, the sludge tends to settle if the system hasn't been run. Once you're emptied the system, close bleed screws once system is empty, and close all but one rad. I'd then turn supply back on, (assuming cold feed is clear), and allow the system to 'wash through' one rad at a time until water from drain hose runs clear, get as much crud out as you can. Then refill as normal and add the X400.

 

[smittydj]

Thanks for the advice.

All rads were open and bleed valves too.

I found a honeywell mechanical valve behind my hot water cylinder - opened that and the loft tank emptied.

getting there.

 

[smittydj]

Took spindle out, washer was perished - water flowed after removal - replaced washer - hopefully all is good. Now to refill!!!

Thanks for your help!!!