New build hot water problem

[TedStriker71]

Hi,

Recently moved into a new build and I'm pretty certain there's a problem with the CH/HW that the installers are denying. It's a 'S Plan Plus' system - Ideal boiler with unvented cylinder, dual heating zones and frost thermostat for the boiler in the attached garage. I've had to replace a zone valve on another property recently so googled the **** out of S Plans and reckon I understand it all pretty well in terms of how the zone valves work, how they demand heat from the boiler and how the boiler commands the pump to run (not so sure about the last part to be honest).

So the situation - when the hot water is set to 'ON', the pump runs and the boiler fires up - even if the tank temperature is above the set value on the thermostat. The only thing I can see changing when the water is below the set value is that the zone valve for the HW opens. So what is happening is that the boiler is continuously running and when the hot water reaches the set temperature, the boiler is just heating the water going round the bypass loop as it has nowhere else to go. I did once get a 'L1' error on the boiler when the boiler was set to 'maximum' however that hasn't happened again since I set it to 'eco'. The temp on the boiler display is permanently at around 70-80C and the garage is hot.

I spoke to the builders and they sent round someone from the company that set up/installed the heating system and was told that this is how the system works and that the HW timer should be set so it comes on an off when hot water is required. They said that its normal for the pump and boiler to be running all the time the hot water is turned on. They are going to come round again today to explain the same thing. Problem is, they are 'experts' so if they say it's right then as far as the home builders are concerned that's the end of it. There are 11 similar properties on the road that seem to have the same issues although nobody else is aware of it - as far as they're concerned they have hot water so no problem.

Any advice?

Thanks,
Ted

 

[Hugh Jaleak]

If the cylinder is 'satisfied' then the HW valve should close and cut the power to the boiler/pump. Boiler may have a pump over run to dissipate heat from the boiler once it's stopped firing, but unless there is somewhere else for the heat to be lost, the boiler stat wont allow it to keep firing.

The appropriate Stats will send the signal to the boiler to fire when heat is required, but if the temperature of the water within the boiler is above the Boiler Stat set point, the boiler will not fire, if it's keeping going then either the Boiler Stat is faulty or the heat it is producing is going somewhere.

 

[TedStriker71]

Thanks for the reply.

The tank stat would appear to be working as the HW valve does open and close if I turn the stat up and down past the 'click'. I'm pretty sure we have a fundamental wiring issue going on that's causing constant demand for heat even when the HW thermostat is open and the heating is off.

By the way, when we first moved in, the hot water didn't work at all unless the heating was on (and a thermostat was set above the room temp). The builder's response to this was that the boiler was for heating only and hot water was done by a 'hot water' switch in the airing cupboard, which of course was for the immersion heater. So they have already visited all properties on the road to rewire things so the hot water does actually come from the boiler but left the current mess behind.

The boiler in the garage and the pump in the airing cupboard are definitely both running when the cylinder is above the set temperature - as well as the boiler looking/sounding like it's running, I also checked the gas meter and it is moving. There are no other gas appliances in the house. The garage and airing cupboard are also way hotter than I'd expect them to be so we're definitely burning gas even with the tank stat set to as low as it will go. There is a very 'hot' smell in the airing cupboard and the pipes to/from the boiler are very hot even when the tank stat is well below the temp of the water in it.

The explanation from the heating company is that we should be using the timer for HW as an 'eco' thing. They seem to think it's normal for the pump and boiler to be running all the time the HW is switched on.

We work shifts so have the HW set on 24/7 - it's never been a problem in any other houses and in them it does just as I'd expect, with the boiler occasionally kicking in to top the hot water up or running for longer if there's a lot of HW drawn.

I'm tempted to take a look in the wiring box to see if I can see anything wrong myself but really don't want to go there on a brand new system!

Thanks,
Ted

 

[TedStriker71]

Update... A different heating engineer is here and he seems to understand exactly what the issue is. Watch this space!

 

[nitro23456]

I hate to think what your gas bill will be if has been constantly running

 

[ianmcd]

It is wired wrong , the timer and thermostats send power to the corrosponding zone valve, the zone valve sends the signal to the boiler and to come on and with your boiler the boiler sends power to the pump (pump over run), if it is wired correctly one of the zone valves has a stuck end switch or micro-switch same thing different terms, any decent engineer would suss this in half an hour, not rocket science to test, but IF all the houses are the same then it is definately a wiring issue

 

[TedStriker71]

Just to close this one off, yes it was wired wrongly and if I hadn't been forceful it would have been left like that. I expect all of the similar houses on the estate will have a boiler that runs all the time the hot water is on. That's those that actually know they have gas water heating and don't just use the immersion heater as advised by the house builders.

 

[ETAF]

should you not tell at least your neighbours

 

[TedStriker71]

should you not tell at least your neighbours

I have. At least the ones wh aren't complete ******s! I would hope the house builders would be informing any others (yeah right).

Now its going to get colder I'm sure a lot of people in similar houses on the estate will find out that two of their radiators don't work as the feed and return are both plumbed into the feed pipe so will need holes cut in their ceilings to remedy it.

And they told us not to bother with a snagging survey as they inspect the properties before sale...

 

[Harry Bloomfield]

And they told us not to bother with a snagging survey as they inspect the properties before sale...

Sounds like they are expecting you to find issues (which you have), I would inspect very closely indeed.

 

[ETAF]

I have. At least the ones wh aren't complete ******s!

yep, we all have those

I would hope the house builders would be informing any others (yeah right).

Duck - flying pigs

 

[oph]

As someone who works in construction, I'll bet that them as standard house bashers have little in the way of QA's and comissioning. Certainly won't have an independent commissioning agent witnessing things.

 

[ETAF]

i guess the builders should be sorting everyone out on that estate - or via someone like the NHBC

 

[MeldrewsMate]

The phrase the neighbours should be quoting to the builder is, 'demonstrate that the boiler interlock is working'.