CH advice needed lots of possible solutions...

[hoppaz]

Hi,

I am having some trouble with my CH. I moved into my terraced house two years ago which has an open vented heating system with baxi back boiler and has 6 radiators. The hot water / boiler side of things is perfect.

The CH system on the other hand operates on what I believe is called a flow and return system. It is also microbore. Ever since I moved in the bedroom radiator has never got hot. It used to get a little warm but that is it. Now it does nothing.

My Grundfos CH pump (UPS 15/50) has always been noisy and when I moved in my Dad who knows a little about plumbing turned the pump up to 3 from the 2 setting to try and get the radiator hot. It didn't and has remained on that setting ever since. I should also add that the system is balanced fine.

Other than the above problem which I lived with as my house was always warm I never had any problems.

That is until this Autumn...

After sitting all summer I turned on the CH system and I noticed that my bathroom radiator would not come on either so I decided to add some Sentinal chemical flush which I left in for 5 and 6 weeks (it kind of worked as both the bedroom and bathroom radiators started to get warm but not hot after a few weeks of it being in the system).

Anyway yesterday I flushed out the system. Conveniently I have a stopcock which turns off the water supply to the header tank in the airing cupboard where my boiler and pump is. I turned this off and ran a pipe to an outside drain. A lot of black water came out and I opened the bleed valves on the upstairs radiators to drain the system etc. The only thing I didn't do but I have found out today is that I didn't isolate each radiator and flush them individually which I will do tonight to try and clear and more dirty water.

Failing this I am out of ideas. Anyone have any other ideas what the problem could be?

I could replace the pump, some of the valves or the radiators in question but don't want to do if it's not necessary. I could flush it a few more times to see if things change but just want some advice to avoid me wasting time.

Many thanks in advance for anyone's help!

 

[landyandy]

How are you flushing your system?
Or are you just draining then re-filling?
There could be crud in your header tank which you will be introducing into your system.

 

[hoppaz]

How are you flushing your system?
Or are you just draining then re-filling?
There could be crud in your header tank which you will be introducing into your system.

There is no crud in the header tank it is very clean as is the water (I have seen inside it). To flush I am draining the system then turning the stop cock back on which allows the header tank to re-fill to flush. It does provide a fair bit of pressure doing it this way although I didn't turn every radiator off and then each one back on individually yesterday.

This is what I intend doing tonight though as it won't take long to drain and flush the system again.

 

[namsag]

Blockage will be in the manifolds so either cut them out an clear them or try and rig up something so you can stick a hose on mains pressure onto rad valves this sometimes works.
Do you have twin entry rad valves or valve either side of rad

 

[hoppaz]

Blockage will be in the manifolds so either cut them out an clear them or try and rig up something so you can stick a hose on mains pressure onto rad valves this sometimes works.
Do you have twin entry rad valves or valve either side of rad

I have valves either side of all the radiators.

 

[JohnD]

you say you used Sentinel for 5 or 6 weeks. Was this X400 or what? Did you flush the system at the end of this period to remove the loosened sediment?

I see you are getting black material out?

can you do simple DIY plumbing? And can you afford £100?

Did the system work correctly in the past?

have you balanced the radiators?

 

[namsag]

Rig something up then and blast water up through the valves see if it shifts it, easiest for a diyer

 

[hoppaz]

you say you used Sentinel for 5 or 6 weeks. Was this X400 or what? YES Did you flush the system at the end of this period to remove the loosened sediment? YES I DID THIS YESTERDAY

what colour material comes out? INITIALLY BLACK THEN RAN CLEAR EVENTUALLY

can you do simple DIY plumbing? YES

Did the system work correctly in the past? KIND OF APART FROM THE BEDROOM RADIATOR WHICH JUST GOT LUKE WARM

have you balanced the radiators? YES

 

[hoppaz]

Rig something up then and blast water up through the valves see if it shifts it, easiest for a diyer

I can simply turn on the stopcock which starts filling the header tank and system back up which does provide a lot of pressure as the water streams out of the hosepipe down the drain. Do I need something more powerful??

 

[namsag]

Pressure from mains will give you far more power than a header tank also as your draining it you are not draining the affected pipe as it will drain somehow.
by connecting it up to each valve you are making sure that pipe is clear all the way past the manifold

 

[JohnD]

if you mean the bathroom radiator never got more than lukewarm in the past, it might be it has a poor supply due to a pipe design error. If it slowly got worse over time it might be accumulated sediment. If you turn off all the other rads it should get hot unless very badly obstructed.

there is a picture (somewhere) of how to connect the water supply pipe (that usually goes to the ball-cock on the F&E) to the vent pipe, to help squirt out blockages. If you close most rads but have one open at a time this may blow out soft blockages.

Sentinel X400 loosens sediment but you might have a hard blockage that you will have to cut out and splice in new pipe. If you hold a strong magnet to the suspect pipes and joints, you will find it is attracted to the copper pipe where there is a mass of black iron oxide sediment inside.

As you can do plumbing and afford £100, consider buying and fitting a Magnaclean on a 22mm vertical return pipe. This will trap any circulating black sediment flowing in the water, preventing future blockages and catching whatever gets loosened by chemicals or flow. It carries on working permanently and you can empty out the stuff it has caught. You can never get all the dirt out with flushing.

I am just a householder.

 

[JohnD]

here we are - no. 5 (I had been thinking of no. 24)

//www.diynot.com/forums/viewtopic.php?t=37170&start=0

 

[hoppaz]

Thanks for the replies guys.

The radiator in the bathroom has gotten gradually worse but the bedroom one has always been the same.

I will try the flushing with each individual radiator isolated to see if that works or helps.

If not I guess it's a case of taking each radiator off and flushing the pipes on either side.

 

[hoppaz]

Right I turned off the stopcock which supplies water to the header tank in the loft. I then drained the system and then turned each radiator off and turned the stopcock back on. I then went through the house turning each radiator on for a few minutes and then off before moving on to the next one. Each time i went own stairs to check the outflow of waste water which was good in every case and you could hear each radiator emptying.

After every radiator was done I then refilled the system and bled the radiaotrs and pump for air before balancing the system.

Now I have an additional problem. The main sitting room radiator has now gone cold so that means I now have three radiators not working.

Checking the pump I gave it a knock and I heard a bubbling / gurgling sound which sounded like it then got pushed down the outflow pipe down into the floor.

One question - will the water returning to the pump be a lot colder than the water traveling away from it. To touch there is a dramatic difference. The pipe which has water going out is too hot to touch but the one coming back into the top is just warm. The pump is still on setting 3 and is humming but not as bad as it was when it was pumping dirty water around.

I am hoping this additional info will help to make sure that I do have a blockage.

 

[hoppaz]

Just to update the thread over Xmas I flushed the system a few times to no avail. I still have two radiators which aren’t warming up, the bathroom one and the bedroom one.

I drained the bedroom one by isolating the valves and taking one end off. It has a trv valve and I checked this and it’s working (not stuck). The pipe leading up to the valve at the other side of the rad gets hot but hot water does not go into the radiator. After draining and connecting it back up you can hear water entering the radiator when you open the valves. I am not sure if the in-flow pipe trickles in but you can definitely hear water entering the radiator it just wont get warm.

This is the same with the downstairs bathroom one. I replaced the rad over xmas and it does get a little hot now at the top but not fully hot. I have the benefit of a drain point on this radiator so I can drain directly into a bowl. When I open each of the valves on this radiator one side allows water to rush out of the drain point but when I open the other valve fully it merely trickles out. This radiator does not have a trv. Again the in-flow pipe is hot leading up to the radiator but the rad does not heat fully.

Could this mean that the in-flow valves are blocked / broken?

I tried dosing with Sentinel x800 at the weekend with another good flush but there has been no improvement. The pump has quietened a bit but can still be heard circulating so I guess that is working as it should.
I have also isolated each rad and just had the pump running on full to try and get them going but in both cases it had no effect.

Any other suggestions would be welcome.