Temporary increase in hot water pressure

[j.edwards]

For the last month or so, I’ve noticed that if I switch on the hot water (can be a hot tap or even the shower) the water that initially comes out is of a higher pressure than I’ve ever noticed before. After a second or two, the pressure drops to a normal rate that I’m used to.

We have an Ideal H18 boiler with a Kingspan Range Tribune XE unvented hot water tank.

In the last few weeks we’ve had a leak somewhere along the hot water feed for our shower which is now fixed and currently dealing with a seized motorised valve that supplies the heating to the majority of our home. The plumber who attended today confirmed this and was unable to move the switch from auto to manual.

We’ve only been in the home for a year and so had a couple of questions that I hope you can help with:

1. Typically how long should a motorised valve last before seizing up?
2. Could the leak, faulty valve and fluctuation in hot water pressure be linked or just a pure coincidence?
3. I’ve taken a look at our pressure relief valve on the hot water tank and it turns a little both ways without the feeling of any resistance. Is that normal?

 

[Exedon]

Motorised valves depends -- make - how much use - how clean is system?
Seen them fail after month in others many years old.
Your always likely to get a small drop in pressure as it stabilisers when tap opened.
Do not touch any of safety controls on a pressurised cylinder, you need a engineer with G3 qualifications to check them.

 

[Madrab]

EV pre-charge pressure is usually to blame when the the initial HW pressure changes from the usual - the cylinder's pressure climbs when it is heated and the EV should equalise that pressure, if it isn't then it may need a little adjustment.

The PRV will have slack before the sawtooth raises the cap against the spring, as suggest though no need to play with that.

Time to get a qualified unvented bod in to service the cylinder serviced I would think.