Intermitent lack of water from hot tap -

[thewatergirl]

There is a problem with my water heater. I keep losing pressure from my hot tap. It's on all taps so I know it's not a air lock in the tap. I also know it's not the mixing valve as the died a couple of months ago and was replaced. What happens is the water coming out of hot tap is just a trickle. The trickle is cool so it's clearly the cold the blending valve mixes in so i don't boil alive in the shower/bath. It comes back on if left for a while. There seems to be no set pattern to this. It happens a couple of times a day although as i'm only in morning/evenings I suspect it would be more frequent if I used water more often. I've had my immersion looked at and there seems to be no obvious problem. Nothing is missing/broken/damaged etc. The immersion runs on economy 7 and my house is all electric I have no gas heated hot water. When I turn the boost switch on the hot water was running fine within 10mins. I thought this was just coincidence. I left my boost on accidentally for three days this week and not once did I have a problem with my hot water. I noticed and turned boost off and the problems started again. The two things must be related? I've tried googling and it suggests the mixing valve is faulty or an airlock in my tap. I'm stumped. Any suggestions anyone please?

 

[galaxy_plumbing]

water heater, do you mean direct cylinder with 2 immersion heaters? you might off answered your question, could be lot of limescale in cylinder and on immersions so takes long time to heat up as you said its fine when left on. when left on boost does the water get hot as it should?

 

[thewatergirl]

water heater, do you mean direct cylinder with 2 immersion heaters? you might off answered your question, could be lot of limescale in cylinder and on immersions so takes long time to heat up as you said its fine when left on. when left on boost does the water get hot as it should?

Yes it's a direct cyclinder with two heaters, one on E7 and one wired to day if you run out. It's not that the water isn't hot but more like something is stopped the water getting to the taps. It comes out as a trickle. Just a little trickle which I believe to be the cold water the mixing valve lets through to make sure the water isn't too hot?

 

[galaxy_plumbing]

When I turn the boost switch on the hot water was running fine within 10mins. I thought this was just coincidence. I left my boost on accidentally for three days this week and not once did I have a problem with my hot water.

so with boost on it works or not? if it was a blockage it wouldnt work with boost as well so probably seems like element/limescale problem. how old is the cylinder/elements?

 

[thewatergirl]

so with boost on it works or not? if it was a blockage it wouldnt work with boost as well so probably seems like element/limescale problem. how old is the cylinder/elements?

Yes it works on boost. The problem only occours now and then but never if I have boost on it seems. The cylinder is about 10 years old I guess was in when I moved in. The stats and blending valve are less than 6months old. I don't understand why the water only goes off sometimes. It never happens mid flow either just when you turn a tap on sometimes.