Losing pressure in CH when hot tap goes on

[Anthony Mayfield]

Hi,

I've been trying to fix my Linea 24 because the central heating wasn't working. After trying different things I pull off the diverter motor and the hot water started running through the central heating. I've now ordered a new motor and I can see it working whereas the other one wasn't. However for some reason I'm not getting any CH still! I've tried the trick of pulling off the diverter motor but still no joy now.

The odd thing is is that when I turn on the hot tap then I will get hot water out for a bit but then the boiler will make a sound like a kettle cooking and then the pressure will drop and the boiler will go off with a 02 (Overheat) warning. I restore the pressure and try again and the same thing happens. The hot water was working fine until I changed the diverter value, does anyone have a clue what is going on?

Many thanks,

Anthony.

 

[ianmcd]

when you say the boiler goes off with a pressure warning , do you mean that you get an 04 fault code ?

 

[Anthony Mayfield]

Hi Ian, sorry I don't know where I got low pressure from but after checking the manual it's the overheat warning (02), I've now updated the initial question.

Since speaking I've put the old diverter valve back on which is locked in the up position. As I put it on I heard water gushing into the pipes and the system appears to now work again. I'm going to check the new motor tonight, I've not sure if I've mixed the wires on the connection around (I took them out to test the old motor), perhaps this could have done it...

 

[ianmcd]

if you remove the actuator motor the rads should heat up, check that your pump is not blocked or sticking.

 

[Anthony Mayfield]

I had indeed mixed up the two leads when I tested the old motor. After putting them back and placing the new motor back in a now successfully have hot water and a hot out flow pipe .

However I still don't have hot radiators The radiator closet to the boiler is lukewarm at best. Although the flow out pipe is now really hot, the flow in pipe is not hot in the slightest, it's like the pump isn't working but it sounds like it's whirling away and if I under the screw water will come out quite fast. I also used the safety valve to flush out the water and check that I could turn inside the pump with a screwdriver and it seemed fine.

 

[ianmcd]

doesnt mean the impellor is not sludged up

 

[Anthony Mayfield]

Thanks, I'll pull off the head tonight. I haven't been able to do it yet as it looks like the heads on my flow in and flow out valves are buggered, but I guess if I just release the pressure with the safety valve it will drain the system enough to take off the head. I did create another post about the flow valves before and it seemed the common consensus was that they needed to be replaced.

https://www.diynot.com/diy/threads/turning-off-valves.487853/#post-3975154

 

[Anthony Mayfield]

I am planning to get a pro in to replace the whole boiler soon, I'm just trying to put it off until I have done up the kitchen and living room as otherwise it's going to kill that budget and delay it.

 

[ianmcd]

Dont touch the flow and return isolator valves

 

[Anthony Mayfield]

Cool, thanks, I'll just drain through the safety valve.

 

[Anthony Mayfield]

I've taken off the pump and clean it and it appears to be working fine, although old. It's got it's a Grundos UP 15-50 and is meant to have three different speeds. Online it says that you just flick a switch but mine doesn't have a switch just this cryptic arrangement of wires from the capacitor. Do you know how I can change the speed?

 

[AGAS]

also


now you better change the safety valve , its a safety valve not a drain off

 

[ianmcd]

I've taken off the pump and clean it and it appears to be working fine, although old. It's got it's a Grundos UP 15-50 and is meant to have three different speeds. Online it says that you just flick a switch but mine doesn't have a switch just this cryptic arrangement of wires from the capacitor. Do you know how I can change the speed?

View attachment 126376

you are looking at the wrong end , it is the impellor, the water end you should be looking at

 

[ianmcd]

also


now you better change the safety valve , its a safety valve not a drain off

@AGAS I knew that was going to come up and not being critical in anyway, as we both know that using the Safety valve discharge is frowned upon now for reasons that we both know, but it actually states in the MIs for the linea to drain the boiler to swap the pump that you use the safety valve , dont shoot the messenger but it does state that

 

[AGAS]

@AGAS I knew that was going to come up and not being critical in anyway, as we both know that using the Safety valve discharge is frowned upon now for reasons that we both know, but it actually states in the MIs for the linea to drain the boiler to swap the pump that you use the safety valve , dont shoot the messenger but it does state that

Imo more fool the manu's for advising that also this boiler is getting on now which perpetuates the problem,
Still my message still stands OP you better replace the PRV to remove the hassle/ time and future problems ,