Not mine, but when they use just the central heating, 'hot' water is now just lukewarm, but when electric immersion is switched on, it gets boiling hot. Anyone know what the likely fault may be?

Is the timer set to heat water or just central heating? 

Controllers will have 2 separate lots of settings for HW and CH.

If it's just set for CH the water won't heat up 😉

5 minutes ago, Turvey said:

Is the timer set to heat water or just central heating? 

Controllers will have 2 separate lots of settings for HW and CH.

If it's just set for CH the water won't heat up 😉

no change to timer setting, use to work fine, now it doesn't...

Hot water actuator not opening? 

I "THINK" that you should be able to manually open it to allow the water to be heated. 

If you can open manually then it'll probably be the wee motor on top that's faulty (in my experience anyway) 

That's great, at least I won't sound dumb when organising a proper man to come out and fix! LOL At least it's not an 'emergency' repair as the immersion still works fine...

 

Pretty sure it'll be the same if it's HW or CH.

 

 

 

If you do work out that it's the motor that's gone then it's really simple to change 😉

Buy a motor for about a tenner and it's 2 electrical connections and 2 mounting screws underneath a cover held on by 1 screw. 10 minute job 👍

Check both the stats first, stat in immersion heater probably needs turning down, cylinder stat for hot water via boiler may need turning up, but also as said make sure the valve is operating.

2 minutes ago, KenM said:

Check both the stats first, stat in immersion heater probably needs turning down, cylinder stat for hot water via boiler may need turning up, but also as said make sure the valve is operating.

I know nothing, but would think something has gone faulty. Like I said, it use to work perfectly, now it doesn't...

Hi Stephen (Steven ), the fault is most likely to be the motorised valve that controls the heating and hot water loops and what usually fails is one or more of the microswitches. That's much more likely than a failure of the motor itself.

Back in the day there would have been separate valves for heating and hot water but nowadays they're combined into a single 3-way valve. This, to me, is a horrible kludge of a design which uses spring return and relies on reducing the motor torque (using a resistor switched by one of the microswitches) to balance the spring force to keep the valve in it's mid position where it feeds both loops equally. A switch failure will result in it driving to full HW or full CH.

A competent electrical engineer (such as me ) can easily replace a faulty microswitch which is a lot cheaper than buying a new motorised head. What I've done in the past is keep a spare head handy so I can do a swap for a speedy repair and then replace the failed switch at my leisure.

As @Turvey says there should be a latching mechanical lever on the head that can be used to move it into the mid-position

@mjt I presume you're a heating engineer or similar?

I've got a situation that I know what the solution is but I don't know if it exists! 😀

Basically our house has got an annexe I suppose you would call it, where our 2 sons bedrooms and bathroom is. The controller for the whole house CH and HW is downstairs and being a bit lazy when they go for a shower they sometimes 'forget' to come down and boost the HW if it's outside of the hours that the timer is set for. 

So, is there an affordable timer/controller that has a remote wireless separate controller that is able to boost the HW for an hour that could be installed next to their bathroom? 

Twice this week I've gone for a shower and it's only been lukewarm!!! 😡

3 hours ago, Turvey said:

I presume you're a heating engineer or similar?

No, I'm just an electronics engineer who has fiddled around with his heating system when something's gone wrong.

I don't have the answer to your question, I'm afraid. I can only suggest you do a web search or hope there is someone on the forum who can help. My daughter has recently had a new boiler which can be remotely controlled with a phone app so I would imagine there must be something out there that would do what you want.

3 hours ago, Turvey said:

@mjt I presume you're a heating engineer or similar?

I've got a situation that I know what the solution is but I don't know if it exists! 😀

Basically our house has got an annexe I suppose you would call it, where our 2 sons bedrooms and bathroom is. The controller for the whole house CH and HW is downstairs and being a bit lazy when they go for a shower they sometimes 'forget' to come down and boost the HW if it's outside of the hours that the timer is set for. 

So, is there an affordable timer/controller that has a remote wireless separate controller that is able to boost the HW for an hour that could be installed next to their bathroom? 

Twice this week I've gone for a shower and it's only been lukewarm!!! 😡

If your cylinder is well lagged, put the programmer on "once", instead of "timed" or "twice". That way, it comes on, on the first on period of the day, and stays on until the last off period of the day, and ignores everything in-between. The cylinder stat should shut the boiler down when the cylinder reaches temperature, and if someone uses the shower during the day, it will automatically switch back on and heat the water up again. If no one uses it during the day, it might switch on now and again for a few minutes each time just to top it up and keep it up to temperature. 

Only reason I say if its well lagged, is if it isn't and the heat is escaping, then it will switch on more often to keep it hot, and could end up costing more money 

46 minutes ago, Apollogary said:

put the programmer on "once",

That's what I have. My Hot water comes on at 7:00AM and stays on until 10:30PM. The boiler only fires up when I've been using the hot water.

We used to leave the boiler on all day but quickly found out that it went through oil quicker than a 50 year old Ford Escort! 😀

 

Ah

Don't really know what to say there then. If its on all day only for hot water and not heating as well, it shouldn't be switching on very often at all. Maybe the cylinder stat is faulty and not switching off when temperature is reached? Though you would notice that the water gets incredibly hot. Unless boiler temperature is set low

Hiya

A few options here, assuming rads are getting up to temp, h/w could be a failing 3 or 2 port valve (depending on system) maybe a bit of a blockage in the cylinder return, but most likely the valve stopping circulation through the coil.

Of course if the heating is not working as normal it might be the pump or possibly an issue with the boiler.

Bit like the car really if you know what youre doing its easy, if you dont its not.

Cheers DD