Bleeding central heating rads issue

[ksareen]

Hi all

I've just moved from a COMBI boiler system house to a house with conventional gravity fed DHW and pump based CH system. The EXPANSION TANK (at the top), the HEADER TANK (in the middle) and COPPER TANK (at the bottom) are in the first floor airing cupboard. The boiler is a POTTERTON PROFILE installed in the kitchen downstairs with a PUMP and motorised valve.

I've recently had to put 2 towel rails in the upstairs toilet and bathroom, so had to drain some water to get my soldering done.

The issue I've now is trying to bleed upstairs rads as water does not seem to be coming from expansion tank to feed them. The downstairs ones are OK as I don't think water was drained that much.

I've already cleaned the expansion tank, there was lot of red (iron rust) and limescale sludgy water there. I also replaced the gate valve at the bottom of expansion tank as it was looking a little rusty. The expansion tank is again filled up with new water from ball valve and the gate valve is open, but still can't get the water to the radiators. I am trying to bleed them one by one but none of the upstairs ones have bled yet.

The bleed screw at the pump gives a few drops of water when its not running, but does not give out anything when its ON (I am actually not sure if I am supposed to open the bleed screw on the pump when the boiler is running). In fact the system makes a bit of air sucking noise when the pump is running with the bleed screw OFF/ LOOSE.

There is also a 3 port TOWER MP3-22C motorised valve near the pump/ boiler but don't know much about how it works or if I am supposed to do something with it when trying to bleed the rads upstairs. Its on AUTO mode at the moment. There is also a paddle position indicator on the side (A-B)? What does this indicate?

The CH and DHW were both working OK before. DHW is working fine now, CH has not been checked as rads are mainly empty upstairs.

Thanks for your help in advance..
Cheers..

 

[grahamgas]

Have you got a drain off cock, on your rad system somewher downstairs.
If so it is possible to put a hose on it and top the heating system up that way.

In regards to the motorised valve, if there is a manual position on it, move it to the manual position.This helps the filling and venting procedure as all routes for the system water are open.

Opening the vent screw on the pump, whilst it is running is more than likely going to be pulling air in to the system.

Hope this helps

Graham

 

[ksareen]

Thanks Graham

There are 2 drain off cocks, next to each other, I don't know why.
I used 1 of them to drain the system partially when installing new towel rails upstairs. I will try to fill the system through mains pressure from there.

But wouldn't it be like curing the symptom and not the cause. Even if it works, the expansion tank would be only used as overflow and not its full design potential.

Great help anyway to keep me moving forward. I will try the manual setting on the motorised valve. Do I need to then turn the DHW ON to bleed the rads upstairs?

 

[grahamgas]

When you drained down, did you drain all the contents of the F&e tank through the pipework.
If so, I would bet my mortgage that there is some crud stuck somewhere.Filling from bottom to the top, may shift this.

Had a similar situation last week.Turned out that the cold feed pipe from the f&e tank, didnt have any fall on it at all.This could be another symptom.

Regards

Graham

 

[doitmyself]

This is the important bit.

There is also a 3 port TOWER MP3-22C motorised valve near the pump/ boiler but don't know much about how it works or if I am supposed to do something with it when trying to bleed the rads upstairs. Its on AUTO mode at the moment. There is also a paddle position indicator on the side (A-B)? What does this indicate?

The motorized valve controls the flow of water from the boiler to the rads and the coil in the HW cylinder. It can be take up three positions:HW only, Rads only or HW and rads. It is controlled by the timer, room stat and cylinder stat. A is the rad, B the HW side. The indicator will show which position it is in.

Normally the lever in the slot should be in the auto position, but when you are draining and refilling you need to move it to the MAN position and lock it in place. There are several ways if doing this: pull lever out/push lever in (gently) or there is a place where the lever will catch.

You need to:

1. Lock the valve in the MAN position and wait for the rads to fill up
2. Bleed all rads - downstairs first
3. Turn the pump to max (usually 3)
4. Turn on the heating and let the water circulate for half an hour.
5. Turn off heating and let it go cold
6. Repeat 1 and 2 if necessary
7. Reset pump to correct speed.

If you have drained a lot of water while fitting the radiator, you should add a bottle of inhibitor to the system. The best way doing this is as follows:

1. Tie up the ball valve in header tank
2. Drain some water from the system until the level in the header tank is just above the bottom outlet. Don't forget to close the drain valve.
3. Add the inhibitor to the tank
4. Untie valve and let tank refill.
5. Repeat 1 and 2
6. Repeat 4

 

[shaunhighcock]

Hi all

I've just moved from a COMBI boiler system house to a house with conventional gravity fed DHW and pump based CH system. The EXPANSION TANK (at the top), the HEADER TANK (in the middle) and COPPER TANK (at the bottom) are in the first floor airing cupboard. The boiler is a POTTERTON PROFILE installed in the kitchen downstairs with a PUMP and motorised valve.

I've recently had to put 2 towel rails in the upstairs toilet and bathroom, so had to drain some water to get my soldering done.

The issue I've now is trying to bleed upstairs rads as water does not seem to be coming from expansion tank to feed them. The downstairs ones are OK as I don't think water was drained that much.

I've already cleaned the expansion tank, there was lot of red (iron rust) and limescale sludgy water there. I also replaced the gate valve at the bottom of expansion tank as it was looking a little rusty. The expansion tank is again filled up with new water from ball valve and the gate valve is open, but still can't get the water to the radiators. I am trying to bleed them one by one but none of the upstairs ones have bled yet.

The bleed screw at the pump gives a few drops of water when its not running, but does not give out anything when its ON (I am actually not sure if I am supposed to open the bleed screw on the pump when the boiler is running). In fact the system makes a bit of air sucking noise when the pump is running with the bleed screw OFF/ LOOSE.

There is also a 3 port TOWER MP3-22C motorised valve near the pump/ boiler but don't know much about how it works or if I am supposed to do something with it when trying to bleed the rads upstairs. Its on AUTO mode at the moment. There is also a paddle position indicator on the side (A-B)? What does this indicate?

The CH and DHW were both working OK before. DHW is working fine now, CH has not been checked as rads are mainly empty upstairs.

Thanks for your help in advance..
Cheers..

Blocked cold feeds are a right pain in the bum, back filling the system via the drain valve is the quickest and easiest way just be careful you don't fill up too quickly.

 

[ksareen]

graham, shaunhighcock

I think you are right. There is a blockage in the cold feed from F&E tank. I wished it was at the gate valve, but alas its not there. I will carefully reverse-fill tonight.

When I drained the system (partially) through the drain cock on the pipework, the water level in F&E tank did not move at all. Hence I had to clean it manually by undoing (and changing) the gate valve.

Also, not sure what you mean by no fall on the F&E tank. The gate valve is on a 15mm falling copper pipe underneath the F&E tank, the same pipe then travels to below the copper tank, I can't see from there onwards, I hope it feeds the radiators somehow?

One silly question through: I've 2 drain cocks next to each other on 2 parallel pipes running from upstairs to ground floor. Are they supposed to form some kind of loop (for cleaning the system etc)? Would it matter which one I use to reverse fill the system/ remove blockage?

doitmyself: This was great piece of information, very helpful. I will abide by your instructions when I try to bleed tonight.
Regarding the inhibitor, I don't think the system has had any in the past going by the amount of sludgy red water I picked from the expansion tank. I 've got some cleaner + inhibitor for the system once its ready with all the rads working. Should I add these now or wait till winters as the CH is obviously off, thanks to some fine weather lately?

P.S Excellent help guys, I can't belive I've had so much help on the first day itself. This forum rocks and so do you! Many thanks once again..

 

[doitmyself]

The gate valve is on a 15mm falling copper pipe underneath the F&E tank, the same pipe then travels to below the copper tank, I can't see from there onwards, I hope it feeds the radiators somehow?

This pipe should connect to the pipe from boiler to pump. You should also have a vent pipe (22mm) which hangs over the top of the F&E tank. The order is: boiler; vent; feed; pump; motorized valve.

I've 2 drain cocks next to each other on 2 parallel pipes running from upstairs to ground floor. Are they supposed to form some kind of loop (for cleaning the system etc)? Would it matter which one I use to reverse fill the system/ remove blockage?

One will drain the flow, the other the return. Doesn't matter which one you use.

Regarding the inhibitor, I don't think the system has had any in the past going by the amount of sludgy red water I picked from the expansion tank. I 've got some cleaner + inhibitor for the system once its ready with all the rads working. Should I add these now or wait till winters as the CH is obviously off, thanks to some fine weather lately?

If the water is dirty, uses the cleaner first; just follow instructions on the can.

Which products do you have? Some cleaners can be left in longer than others.

 

[moogwai]

i would cut out and replace where the cold feed from f & e tank meets the system pipework....this spot always gets blocked up,just make sure you get as much water out of the f & e tank as possible or you will get wet, or buy a rubber bung set and stick it in the feed hole.
what colour was the water when you drained it down? if it was black/rust colour i would suggest a powerflush to clean out the system completly and then add inhibitor yearly to protect the system...maybe even add a magnaclean/fernox tf1 to the system to catch any future crap that may get about your system.

 

[Toddyplumb]

£0.50 says you have pump over problems, just a hunch

 

[Mbear]

Easiest way to find a choked cold feed is to use a fridge magnet over the suspected area, it sticks to the choked area(magnatite). This gives u a good idea of the extent of the chokage and where to cut. Trust me the magnet works. Best of luck

 

[ksareen]

Thanks for all your help folks!

doitmyself,you are right. Its a vented system with a 22mm vent pipe over the F&E tank.

moogwai, I would've agreed with you, but there is gate valve on the cold feed from FE tank to CH pipework, about 12 inches from the FE tank. It was quite rusty, so I've just replaced it with new. Now if there is water in FE tank, and if I open the gate valve with other end disconnected, water flows freely from the FE tank.
Water in the tank was rusty red colour, so powerflush sounds like a good idea. Any idea about the costs? Its a small house with 6 rads and Potterton Profile boiler.

Toddyplumb, could you plz explain what a pump over problem is?

Regarding back filling the system through drain pipes, I had a few attempts with little success. The drain plug is too small for my garden hose, so I applied some electric and PTFE tape on top of copper plug, then connected my garden hose, but still leaked a little, not as much as the screw itself that leaks like hell when I open it a bit for draining/ refilling.

Tried both the drain plugs (flow and return) and unscrewed the gate valve so I could see the water coming back into the FE tank (presuming that the blockage was cleared). That did not happen at all. So I opened the bleed valves of a few radiators but water was getting everywhere in the kichen.

So a few threats from the missus forced me to abandon for today. Went back to airing cupboard, connected the gate valve and opened the mains cold and then the gate valve for FE cold feed into CH pipework.. Voila, 2 and half rads bled in quick succession but then it fizzed out.

Guess I will have to try with a thinner hose to reverse fill properly but these drain screws are horrible. I will upload a couple of pics of the setup tomorrow.

 

[Toddyplumb]

ksareen, of course.
Once you are back up and running have a look in the expansion tank with various combinations of the system running ie Heating only , hot water only and finally both on .
If water runs from your vent pipe into the FE tank you have pump over. Rusty red water is a sign as you are aerating the water and circulating it through your rads, o2 + iron rads = rusty red water

 

[moogwai]

moogwai, I would've agreed with you, but there is gate valve on the cold feed from FE tank to CH pipework, about 12 inches from the FE tank. It was quite rusty, so I've just replaced it with new. Now if there is water in FE tank, and if I open the gate valve with other end disconnected, water flows freely from the FE tank.
Water in the tank was rusty red colour, so powerflush sounds like a good idea. Any idea about the costs? Its a small house with 6 rads and Potterton Profile boiler.

thats fair enough, but i'm saying the blockage would be where the cold water feed tee's into the central heating pipework...if you see what i mean.
you'd be looking at around the £300 for the powerflush and extra for cutting out and replacing said pipework where blockage will almost certainly be. You should be able to find plenty of powerflush guys in your area but if you have any trouble pm me and we could sort summat out.
hope this helps.

 

[ksareen]

doitmmyself
I forgot to mention that the cleaner I bought is called Killrock from B&Q.
Still not at stage where I can use it as cold water is not flowing from FE tank into the rads.

moogwai, thanks for the cost estimates. I am going to defer powerflush for the next year as I am going to change boiler position after an extension, so will probably get it done then.

As of now, its not going very well. The DHW is not warming up (barely lukewarm) and the boiler/ pump are making a few noises of bubbly water slushing through them every now and then. I guess there is lot of air in the system.
Does the thermostat on the copper tank (currently at 60) feedback to the boiler or is it only for the immersion heater? I think it was foolish of me to bleed the pump when it was running. I've added more air to the system and now have DHW issue as well in addition to CH issue.

I am going to try with a thinner hose tonight to reverse fill the system. Apart from rads and pump (with boiler OFF), is there any other place where I could bleed air like copper tank, boiler itself etc? Its a Potterton profile 50e boiler.

Please also confirm that if I reverse fill the system via mains and keep the rads bleed valve closed, shouldn't the mains water clear blockage in pipes and then come into the FE tank? Then I can bleed all rads one by one. The motorized diverter valve is in MAN position at the moment, can't see the position from indicator as its too tight and dark (it seems to be in MID position to me though).

Mbear, if the blockage does not clear, I will use magnets and update on here. Thanks for this suggestion.

I am attaching a few pics of the set up for your reference.

Cheers..

 

[moogwai]

mate it would seem you are slightly out of your depth....if i was you i would really look at getting a plumber in before you do any damage to your system.

 

[ksareen]

What is the guarantee that the plumber won't damage the system? Or is it because he can mandate the powerflush bite?
Anyway, I am a learner and not giving up. There are lot of helpful posts on here and I should be able to resolve this one soon.
Thanks for your kind help anyway.

 

[Puddle]

Close gate valve,check the tee in 'pic one' just after gate valve is clear,if not clear,if ok,follow 22mm pipe down to were it tees into system and cut and check (or use magnet as said) there for blockage,if will be in one of the tees most likely
just take your time,you have the nice weather on your side at the moment

 

[moogwai]

whatever you do,you need to get rid of the blockage. just by backfilling the system you probably won't dislodge the blockage,and by the looks and sounds of it you have a single pipe for feed and expansion for the central heating, so if you do get heating working without removing the blockage you in effect have created a sealed system with out any room for expansion and contraction and in turn this could turn very nasty.

 

[ksareen]

well said puddle, I'll follow. The magnets trick is amazing to learn. Many thanks to you and Mbear.

You are right about the weather. Please note that we have just moved into this house and did not have this type of heating system before (I had much simpler combi in my previous house), so please pardon my silly/ basic questions. This is a learning curve. I am working 6 days from 8 to 5, and I do get tired in the evenings. I tried for around 30 minutes yesterday, so I am slow but keen. Will get there for sure with help from here..

moogwai, you are spot on. I am taking blockage seriously and if I cannot get the blockage cleared through mains/ magnets, I will get it powercleaned. Even if I get it unblocked now, I will still get the system powerflushed when the boiler goes on a new extended wall. However, you are incorrect about having "a single pipe for feed and expansion for the central heating". Please check PIC 5 again on my previous post. The 15mm pipe on the right is the FEED, the 22mm overhead pipe on the left is EXPANSION.

I am attaching a pic of the pump and a gate valve next to it. Could some kind soul explain why this gate valve is there and if it could contribute to any of the current issues or help in getting rid of them?

Thanks for your patience with me guys.

 

[moogwai]

right ok...just looked at pic again,ksareen. You are right in saying that the 15mm pipe on the right is a cold feed...but this is the cold feed to the feed and expansion tank.
The cold feed i am referring to is the cold feed to the heating system which is shown on your pic 1, the one with the gate valve on coming from the bottom of the f & e tank.
This 15mm pipe tees into the 22mm pipe which is acting as the cold feed and expansion pipe for the central heating system. The blockage could well be in or around that tee....first place i'd try the magnet test on, i would then trace the 22mm pipe downwards with the magnet to see what you can find.
The gate valve in your lastest pic is the bypass for the central heating system,another place where i have found blockages in the past.
i hope this helps.

 

[ksareen]

moogwai, Yes you are right. Let me find the stubborn blockage today evening and get back..

Thanks for the info.

 

[moogwai]

good luck pal.....let us know how you get on. these things can be a pain in the buttski!

 

[Mbear]

Ksareen

The magnet will not clear any blockage at all.

It will only tell u where the blockage is, it then needs cutting out and replaced with new pipe/fittings

I got the feeling in one of ur posts on page 2 that u thought the magnet will clear the blockage. So I'm just making it clear to u mate

 

[turnpin]

surely the gate valve on the f&e tank outlet filling the heating circuit should not be there I know it will not solve your problem can anyone confirm this?