System Boiler & Magnaclean Queries

[RVS1974]

Hi
I have a system boiler (Worcester Bosch). There is a Magnaclean filter fitted, which I assumed was just on the central heating. Heating was turned on a couple of days ago and the pressure on the boiler has been dropping. Last night I made sure the heating side was turned off, wrapped kitchen roll around all rad valves p/w at each rad end, around p/w below boiler and around magnaclean, re-pressurised to 1 bar and left it until this evening. Pressure has dropped by somewhere between 1/3 and 1/2 bar. Heating definitely hasn't been on. Hot water did come a bit earlier for an hour or so. I did notice the magnaclean was hot (it is located immediately below the boiler).

First question - should the magnaclean get hot when just the hot water is on? I thought the m/c was just attached to the central heating side. Can the HW side mix with the CH side e.g. if the diverter valve is faulty?

Second question - if there are no sign off leaks anywhere on the central heating, what can cause the pressure to drop, especially when the heating hasn't been on? Could it be something to do with the expansion vessel? There is no release of water from the external pressure release valve pipe (bone dry), and when the heating is put on the pressure doesn't shoot off the scale.

I'd appreciate any thoughts.

Many thanks.

RVS6

 

[Deleted member 120897]

I think you’re getting confused with the type of system you have. I think all boilers use the central heating water to heat the hot water, so yes the magnaclean would be hot if you’ve used the boiler to heat the hot water cylinder. As for pressure loss, how much are we talking?

 

[RVS1974]

Hi Chris
It is losing 1/3 to 1/2 bar since last night with the heating off. I cannot find any sign of a leak anywhere

 

[RVS1974]

Unless the leak is in inside the boiler, and I am not going to be trying to take the cover off!

 

[Deleted member 120897]

Unless the leak is in inside the boiler, and I am not going to be trying to take the cover off!

You don’t need to. What I would do is top up the boiler to say 1.5 bar and isolate the flow and return if possible, which should help with identifying if the boiler or system, eg if the boiler is the culprit the pressure will still drop.

 

[RVS1974]

not sure where to isolate the flow and return. Could it be the two black valves on the pipes going into and out of the magnaclean as per the attached photo? I don't like pipes and wires!

 

[Deleted member 120897]

not sure where to isolate the flow and return. Could it be the two black valves on the pipes going into and out of the magnaclean as per the attached photo? I don't like pipes and wires!

No, that would just shut off the magnetic filter. I’ve circled on the photo which to do

 

[RVS1974]

No, that would just shut off the magnetic filter. I’ve circled on the photo which to do

thanks but not sure I should be playing with them, could cause me more grief

 

[Deleted member 120897]

thanks but not sure I should be playing with them, could cause me more grief

That’s up to you, but might be all a plumber would do, amongst checking rads and boiler.