Hot Water a Lot Hotter

[Zambo]

Just had my boiler serviced, and I guess it might not be anything to do with that, but since then my hot water from the taps has been a lot hotter. If the boiler stat was faulty, would that automatically shut the boiler down?

The boiler is turned up to around 2/3 capacity and I've turned it down a notch but this has made no difference to the temp of the water. About 2/3rds down my hot water cylinder I have a strap stat, and I noticed that the water down by the stat has always been a fair bit cooler than at the top, but it's hot all the way down now. Just tried turning it down, but due to wear I can't see the numbers on the pointers on the stat, but I'm sure I set it about 60 degs ages ago

I guess the symptoms point to the fact that that stat is not cutting in to keep the temp down.

Could any of you guys confirm that is probably the cause or provide any further advice. Apart from the obvious danger of scalding, is there any other problems that this may cause, and what temp would the water reach without a stat on the hot water cylinder

Many thanks

 

[Zambo]

Don't really know what I'm doing so I won't delve too far, but I took the top off the box where the lead from the tank stat goes to see if any loose connections. Fiddled about with them but they looked OK. Interesting though when the boiler was due to come on for hot water it didn't, so that may point to the stat being OK because the water is definitely hotter than what I think the stat is set to.

 

[Steelmasons]

If a stat was not fitted to hw cylinder then hot water temp would be controlled via boiler stat.

 

[picasso]

Check your immersion heater hasnt been switched on by mistake.

 

[JohnD]

when did you start running your Central Heating?

If you set the programmer to HW off, CH on, does the cylinder still get hot?

 

[Zambo]

Thanks for your replies so far.

1.Immersion not on

2. Cylinder is still very hot so can't answer re does cylinder get hot if CH on.

When boiler was due to come on to heat water this avro it didn't.

This makes me think it's probably do to with the tank stat. The tank has been getting much hotter than usual all the way down past where the stat is. It used to be quite cool below the stat. Then when I opened the box which the lead from the stat goes to and move the wires around, it seemed to change things and get the stat working again. Otherwise the boiler would have come on again.

Will monitor it for a couple of days and see what happens to the temperature of the hot water.

Do I need to turn the electric off before opening up this junction box, in case some of the connections need tightening up?

 

[Whitespirit66]

There should be a fused spur supplying mains to wiring centre/junction box. Turn off and remove fuse before opening box.

Not sure what motorised valves you've got, but you need to see if it/they are heating the cylinder when heating is on.

Best not to overheat hw, as it can cause scale in hw cyl if in a hard water area.

 

[Zambo]

Think I may have identified the problem, and don't think it's the cylinder stat.

Ran off all hot water until cylinder was cold. Then put CH on and kept W off. Cylinder still got hot. So, do you think I'm right in saying the diverter valve is either limed up or knackered anyway?

I'm assuming that the cylinder stat is not cutting in because with the W off, it's saying W off you don't need me.

John D, I think you were on the right lines.

 

[JohnD]

50p says the 3-port valve

 

[Zambo]

50p says the 3-port valve

Can't afford that, make it 10p

Thanks for your help.

 

[Zambo]

Anyone know if the motor can be repaired on Danfoss 3 port valves?

Both CH and HW come on regardless of which you choose on it's own, and both room stats and cylinder stat aren't cutting in to switch off. However if I have CH on and HW off, although water heats up as well, room stat cuts out at desired temp. Therefore best option until I get this fixed seems to be have heating on when required and leave water off. That way the house is warmed, but will cut out when it reaches desired temperature. Having just HW on means rads are on perm.

I've moved the lever round on the valve and it goes from one end to other freely, so no jamming. I can't tell if the motor is running or not because it sits directly above the pump and of course that is on and both are vibrating.

 

[Agile]

In theory the motor can be replaced but they are usually very difficult on any plastic bodied valve. Often plastic bits are broken too.

Probably easier to buy a new head.

Tony

 

[Agile]

Oops!

 

[Zambo]

A couple of more questions whilst I await to get this sorted.

The assumption I'm making, is that if the 3-port valve has stooped functioning, hot water is flowing freely both to heat the water in the cylinder and the rads.

With CH on and HW off the rads get hot, and the cylinder also gets hot.
When the rads heat the room to the temp on the room stat setting they stop getting hotter, but the water in the cylinder is hotter than the stat temp on the tank.

With HW on and CH off, water in the tank appears only to get as hot as cylinder stat temp. Rads get hot but the room stat doesn't appear to cut in when it reaches that temp.

Assumption - stats only work when you choose that option. Room stat only works when you have CH on and cylinder stat only works when HW on.

Will try CH and HW on all day to see if both stats kick in. Do you think that's reasonable, or am I up a gum tree?

 

[JohnD]

when the CH timer is on, and the CH stat calls for heat, it starts the pump and the boiler.

If, as it seems, the 3-port valve has failed, some of this heat will be going to the cylinder, even though it is not calling.

you can tinker a bit, but it is the 3-port that is not working. It might be the motor, might be the internal ball, might be a wiring fault.

try turning CH off, and HW on, see if the rads get hot

You could turn down the boiler stat to avoid scalding until you get it fixed.