Not so hot water

[superted]

Hi,

I am a first time poster here, with little plumbing/heating knowledge so apologies for the potential newbie mistakes.

We have a hot water issue whereby the boiler correctly heats the water in the cylinder (as has been confimed by more than one boiler engineer) and hot water comes out of the taps but for less than a minute. After that short time the water is warm, certainly not hot and certainly not hot enough for a warm (let alone hot) bath.

We have a boiler insurance policy but this issue is not covered so I want some advice, and potentially a recommendation for someone to fix it. (Chandlers Ford, Hampshire)

It's a reasonably new Worcester boiler, heating a closed/sealed heating system, the boiler has been recently serviced too.
The expansion tank pressure is set to just above 1 bar and the central heating works when it's on.
The hot water issue is not critical as short showers and hot water from the taps is enough for hand washing etc, it's filling a bath that's not possible so the kids want it resolved. It's like the hot water is being mixed with cold on leaving the cylinder as several cylinder pipes are too hot to touch.


I noticed today that the cylinder is a combination cylinder and the top (cold) chamber of the cylinder is completely empty and dry but it looks to have evidence of water in it in the past. There is a feeder pipe (with some bad limescale stalagtites/mites) that I assume is turned off (or blocked with limescale?) hence the dry chamber, should the chamber be empty, is this related??


Ideally I would like some pointers for me to help diagnose this so I am not fleeced by a visiting plumber, once diagnosed an approximate cost range for fixing would be really helpful too.


Thanks in advance.

 

[superted]

Killy Bing - Yes, it's pretty much the same at all hot outlets.

Kris - It certainly looks like the hot outlet goes through a mixing valve. Attached is another pic. Could this be the culprit or the mixing taps?

Thanks again guys

 

[Ermintrude]

Nooooo it's a system mate. Fill the tank on top with cold water.

 

[Ermintrude]

Nooooo it's a system mate. Fill the tank on top with cold water.

Actually is it? System mate has a plate and pumps. Check tank on top has water in it tho and use 2m of 10mm plastic to rod out the feed and vent to ensure not blocked.

Measure temp into and out of mixing valve. They do fail.

 

[superted]

Thanks Ermintrude, yes it is a Systemate, there's a pic in a previous reply.
I will fill the top tank, could that be the reason, or should that be full for another reason? What does that cold chamber do?

What's so bad about a Systemate?

Very unscientifically I measured temp in and out....
Resuts:
- holding the pipe into the valve hurts,
- holding the pipe out doesn't


Cheers

 

[Ermintrude]

The top tank is the transfer fluid to the DHW . Fill it to about 3" below the overflow . Be carful as if it's dry in the main tank u might get some steam and spitting

 

[Ermintrude]

That tmv looks very new! Is it on the right way round ? Was house empty for a while before u moved in

 

[superted]

DHW?? Domestic Hot Water ?
Thank very much, I will fill the tank carefully.

TMV - we have been in the house 5 years, never been changed. The chamber could have been empty that long too ! I have no idea if it's the right way around.

Cheers

 

[Ermintrude]

Is it working now?

 

[superted]

I filled the top chamber, it must have taken about 100L or more as the feed pipe guzzled every jug full. For the rest of the day we had piping hot water ! I even saw steam coming from the water which I have never seen before!


The night time bath for kids was perfect too.


However, this morning was a different story - the shower was cold, and the water has been either piping, or cold throughout the day. The only thing we did last night was turn the heating off (as it was forecast a hot day), it's as if the heating is linked to the hot water ?!?


Bath time tonight was cold water until I turned the tap on fully, it then gave me enough hot for a bath but it was not as perfect as last nights bath.


So.. the jury is still out as to whether the empty chamber was the only issue, I have turned up the mixing valve (assuming turning it counter clockwise towards the plus actually means hotter and not colder), I have checked the chamber, that's still at the correct level since the original fill yesterday.

I am hoping today's cold spell was a one-off and tomorrow it sorts itself out and is like it was yesterday - which was perfect hot water all day !


Thanks for your help so far, definitely improved but no cigar yet


BTW - I have no idea what that chamber is actually for - the auto top up tap is completely blocked, so is not set to refill but the water level does not drop !? - I will obviously check the level periodically but I don't pretend to understand what the point of that chamber is if it's not a feeder to the hot water tank itself.

Thanks