Vokera Linea combi boiler

[tigmol]

My central heating is costing a fortune to run. 3 bedroom mid terraced house, 4 people - £150+ per month in gas being used!
I've had leak seal put through the system. Pressure drops if I put heating off and just leave hot water on. Now when i go to repressurise, I turn the fill loop and can't hear the water rushing in and it takes around 20-25 minutes to get pressure to 1.5br.
Also there's a constant sound when my heating is on, like water running through the system and the pump seems to go continuously.
Any help greatly appreciated cos I can't afford these gas bills anymore!
Thanks

[htg engineer]

Sound like there's quite a large leak somewhere, or the combi fill cold water supply doesn't have much pressure (may be an isolation valve not open fully or a faulty valve on the combi fill).

If you can hear water flowing through the pipes there's probably alot of air in the system. Vent all radiators and pump.

Check for leaks on pipework, radiators and boiler as this will cause the pressure to drop, also check the pressure relief valve, to make sure its not passing.

Keep an eye on the pressure gauge, does the pressure rise before dropping ? if so could be an expansion vessel problem or plate heat-ex problem.

Without more info, can't really narrow it down.

[tigmol]

Hi,

I've been watching the pressure for weeks and it doesn't rise before dropping. I've checked all radiators and pipes that I can get to and no leaks. When I put the heating off I found a drip (every 10 seconds or so) coming from the bottom of the boiler. Doesn't show when heating's on, I suppose because the pipes under the boiler are constantly hot and drying it up. The engineer I had out said he thinks it's the pump and air inlet which he said is all one unit. He advised not to replace it though until the pump packs in completely and it wouldn't be the cause of so much gas being used.
All radiators have been bled. I don't know how to get air out of the pump and neither does my husband!
The water inlet pipe to the boiler comes from the top of the wall down and then runs horizontally for a bit to go under the boiler. Could there be a block in this horizontal part, stopping the water getting through? If so is it easy for me to check/fix myself?

Thanks for your help.