clicking boiler, anytime day or night for a few mins at a t

Hello,
Got a Midas B wall mounted combination gas boiler made by Myson Heating. Firstly; for no apparent reason, day or night at completely random times the boiler makes an incredible clicking sound! It appears the main burner area (from looking at the manual) is trying to ignite!? It happens not because we are turning on any hot taps; early hours of the morning just basically any time. The clicking noise can go on for a few minutes at a time - drives me mad. When the boiler is not working the bar pressure over a few days drops from 1 bar down to zero and I have to fill the system up again to 1 bar. But the system clicks regardless if the bar pressure is low. Another hick-up as well. In the morning I have a great hot shower, a few minutes later my wife will have a shower but there is no hot water?! I have to go and turn the central heating on and the kitchen sink taps to try get the burner to ignite and supply the shower with hot water. The first shower is always ok, but 6 out of 10 times the second shower is the problem.
Another problem. We have a second bathroom about twenty feet away from the boiler which has just a bath. The pressure out the hot tap is not very good plus the hot water is not very hot. By the time the bath is full it just got hot water in so the temp does not require cold water - sames goes for the vanity hot tap? Kitchen hot water tap has the same issue.

I know that Myson no longer make boilers and Baxi took them over.

Anyway, hope someone has some good news or advice for me.

Cheers
Lee

CLicking will be an intermittent electrical problem, possibly a bad solder joint on a pcb, or dirty relay contacts.

Poor hot water performance is usually caused by build-up of sludge , typically in the primary side of the secondary (HW) heat exchanger ( & maybe main heat exchanger too at this age - boiler sings?). This results in low hw temperature for the flow, and overheating of the boiler. It can't get the heat out so it overheats and shuts off until it cools down. Meantime no hot water at all.

Low temp at particular outlets is due to the above, plus too high a tap flow rate for the amount of energy getting into the water - it just comes out too "diluted" = cool. We shower at 38-40 but bathe at about 45.

First problem needs inspection and maybe new parts, sludge can be removed with special methods/machines/chemicals.

Oh - the other problem, losing pressure. It's leaking, innit! Look at the pressure relief pipe which goes out through the wall. Quite often they leak (drip) a bit. That would be because either the valve seat is dirty , or the pressure vesssel needs pumping up. (if there's no "air-spring" for the expanding water to go into, it has to leak out). Other places to look for leaks are rad valve stems and compression connections.

If you've been topping up for long with hard water, you've been introducing "limescale" and fresh oxygen to the heating water which will accelerate sludge formation.

Most combis with these problems were put in on the cheap and haven't been serviced this century!!

Many thanks for the reply Chris.

I had a corgi registered guy come around to see us a month ago and he had no real clue or idea, so naturally I lost faith in the man. But now that you have given me pretty acurate information with regards to my boiler I can atleast print your suggestions and show whoever eventually comes out.

Many thanks again
Lee