Radiator problems!

[Dennie31]

Hi I'm new to this so hope I manage to put in all the info! We live in a bungalow, have 7 radiators, a 2 year old Bosh Worcester condenser boiler, serviced by Bosh, a header tank in the loft and new pump fitted by a plumber early part of the year. The hot water works well but the radiators take it in turns to be cold at the top and hot at the bottom, they worked fine before the new pump.
The header tank is okay, been checked, the radiators have been bled both by us and the plumber, several times.
The rads are fine for a few days and it starts again, normally different ones and sometimes 2 or 3 at a time.
The plumber is normally very good but this time cannot understand what is happening, can anybody help please?

 

[HERTS P&D]

Is the pump the correct way round?

Andy

 

[Dennie31]

Hi Andy, thank you for the reply. I did answer but think I did something wrong! Anyway the pump was installed by a "time served Plumber" so guess we have to trust his knowledge. The husband says it is okay, sorry me I don't have clue but don't think he would have got that wrong

 

[lightning]

Sounds like system is sucking in air, do you have to keep bleeding the rads????

Thanks Paul

 

[Dennie31]

oh yes daily

 

[lightning]

You could make it into a sealed system , that way you can remove header tank and cold feed and vent,
Turn your pump speed down to 1 and raise the vent pipe over the header tank,

Thanks Paul

 

[RigidRaider]

That's an expensive and drastic solution. Why don't you ask if the plumber has tested for hydrogen in the rads, which would indicate oxidation, which would indicate that he forgot to add the inhibitor?

 

[Dennie31]

My husband says when the new boiler was put in it was power flushed and inhibitor put in. Unfortunately the pump that was put in at the time went wrong and we had to replace it. We did take out Bosh insurance for the boiler but that is all it covers, not good as it came across as if all things were covered, so no insurance on the rads or anything else so our local plumber replaced the pump. Should he have added another inhibitor then?

 

[lightning]

That's an expensive and drastic solution. Why don't you ask if the plumber has tested for hydrogen in the rads, which would indicate oxidation, which would indicate that he forgot to add the inhibitor?

It would solve the problem of air getting into your system, if not solved soon then you are going to have a sludged system soon.
Had the same problem on a set up last week who some one had installed, owner had to keep letting air out of rads.

Put a sealed kit on for £200 and he's well pleased no more bleeding rads.

 

[Dennie31]

Thank you for the info and sorry to dim but what exactly is a sealed unit, where would it be put and what would it do please? Very grateful for everybody's help and suggestions.

 

[RigidRaider]

I don't know what's meant by a sealed kit. All I do know is that the plumber will have needed to drain ths system right down when he replaced the pump unless there are isolator valves each side of it. If he did drain down, did he add inhibitor to the system on refilling?

Inhibitor goes by several names including Fernox, it it a concentrate containing chemicals to prevent bacterial growth in the heating circuit and oxidation of the insides of the steel radiators. If you are still having to bleed radiators I would suggest you add another couple of litres of inhibitor to the system; which is an easy job if you understand the simple physics of water levels!

 

[Nige F]

make sure the pump is set on low - 1 . see what happens . 7 rads in a bungaloww should be fine on number 1