Thermmostat just turning off rads, boiler still going?

runswithascript · 18-06-2015 06:15PM #1

Hi

Previously we had a timer and a separate thermostat, no zoned heating. If we had the heat on, either constant/boost/timed, whenever the analogue dial thermostat reached 20 degrees or we set it as low as possible it would turn the oil boiler off.

We now have an entirely new heating system where the rads are on one zone, and the immersion on another. I queried with the electrician who installed the EPC digital thermostat why I could still hear the oil boiler going with the stat turned off and he told me this is so there is hot water.

Is turning the thermostat off the same as setting it to the lowest setting (below the current room temp) so it does not turn the heat on?

Either way, is this normal, or should the thermostat turn the actual boiler off when the stat is turned off/set to the lowest setting (below the current room temp)?

Dtp1979 · 18-06-2015 06:36PM

dusf wrote: »

Hi

Previously we had a timer and a separate thermostat, no zoned heating. If we had the heat on, either constant/boost/timed, whenever the analogue dial thermostat reached 20 degrees or we set it as low as possible it would turn the oil boiler off.

We now have an entirely new heating system where the rads are on one zone, and the immersion on another. I queried with the electrician who installed the EPC digital thermostat why I could still hear the oil boiler going with the stat turned off and he told me this is so there is hot water.

Is turning the thermostat off the same as setting it to the lowest setting (below the current room temp) so it does not turn the heat on?

Either way, is this normal, or should the thermostat turn the actual boiler off when the stat is turned off/set to the lowest setting (below the current room temp)?

If wired correctly, the thermostat will turn off that zone, and subsequently the boiler, if no other zones are calling for heat. What controls have you on your hot water?

runswithascript · 18-06-2015 06:51PM

Dtp1979 wrote: »

If wired correctly, the thermostat will turn off that zone, and subsequently the boiler, if no other zones are calling for heat. What controls have you on your hot water?

Thanks for the prompt reply.

The hot water tank is old so no controls at all, short of some valves I saw in there at one point.

The plumber told me the reason for the weak flow of hot water out of the taps is because the tank needs a separate pump or to be put in the attic (or both?) of our bungalow. We will have him back at some point to do that for us, but not at the moment.

Since there is no separate stat for the hot water is the thermostat working as described best practice? It just seems such a waste that it does not knock the boiler off, considering it is supposed to save money, and I appreciate it is saving some as it turns the rads off.

Wearb · 18-06-2015 07:12PM

If your large water tank is in the the attic, this is what is supplying the hot water pressure.

If your plumper thinks that rising your copper cylinder will improve the pressure in such a system, you need to question your choice of plumber.

Wearb · 18-06-2015 07:21PM

If your new stat turns off the rads, then it must me wired to a motorised valve. The addition of a cylinder timer/stat wired in conjunction with your existing system would give you greatly improved control.

runswithascript · 18-06-2015 09:12PM

Wearb wrote: »

If your large water tank is in the the attic, this is what is supplying the hot water pressure.

If your plumper thinks that rising your copper cylinder will improve the pressure in such a system, you need to question your choice of plumber.

Old cottage, water tank on ground floor. Raising that to the attic would help, no? And do you think we would also need a pump then or would a pump do instead of raising it?

Wearb wrote: »

If your new stat turns off the rads, then it must me wired to a motorised valve. The addition of a cylinder timer/stat wired in conjunction with your existing system would give you greatly improved control.

So if we had that installed, we would still have the existing stat turning off the rads when the room where it is reached optimal temperature, but how would the cylinder timer/stat work. Is that like my description of how things used to be, basically the stat knocks off the boiler? Though if that were the case it would make the existing stat redundant.

Please explain this to me as if I were 10 years old.

Dtp1979 · 18-06-2015 09:20PM

Basically, you need seperaye time and temperature control on your zones, which in your case are heating and hot water. Get a dual timeclock. I'd also get a plumber whose familiar with wiring heating controls, instead of an electrician to wire this.
Ask for it to be interlocked to the boiler as I said in my first post

beanie10 · 18-06-2015 09:22PM

Should be wired as follows:
You need a 2 channel time clock. 1 channel for hot water the other for heating.
The heating Chanel sends power to room stat which sends power to heating motorised valve.
The hot water Chanel sends power to tank stat which then sends power to hot water motorised valve.
Both motorised valves should have an auxiliary contact(usually orange and grey cores).
Join the 2 grey together and join the 2 oranges together. Use the orange as switch wire to burner and pump. Put *permanent* power to grey.

** If a solid fuel with back boiler exists then the wiring here will be slightly different as you will need an electrical interlock,ie solid fuel pump and oil burner should not run at same time.

Wearb · 18-06-2015 09:45PM

The other 2 lads have explained what is needed for extra control. there are other way of doing the same thing, but you need to discuss that with whoever is doing the job.

Most older bungalows have their hot water supply feed from a tank in the attic and it quite happily provides enough pressure for most needs. I have noticed in modern times that there seems to be a need for "power washer type" pressure in taps and especially showers. That may change with the advent of water charges.

Putting the large tank in the attic will be the most trouble free supply for the future, if you are happy with the pressure from it. Otherwise go for a pump and leave the tank where it is.

Dtp1979 · 18-06-2015 09:50PM

beanie10 wrote: »

Should be wired as follows:
You need a 2 channel time clock. 1 channel for hot water the other for heating.
The heating Chanel sends power to room stat which sends power to heating motorised valve.
The hot water Chanel sends power to tank stat which then sends power to hot water motorised valve.
Both motorised valves should have an auxiliary contact(usually orange and grey cores).
Join the 2 grey together and join the 2 oranges together. Use the orange as switch wire to burner and pump. Put *permanent* power to grey.

** If a solid fuel with back boiler exists then the wiring here will be slightly different as you will need an electrical interlock,ie solid fuel pump and oil burner should not run at same time.

There's absolutely no reason why both pumps can't work together at the same time.

beanie10 · 19-06-2015 06:37PM

This causes pitching (Water coming out through overflow in attic) especially as stove gets hot.

OP may not have stove, I just threw it in as an option.

Dtp1979 · 19-06-2015 07:52PM

beanie10 wrote: »

This causes pitching (Water coming out through overflow in attic) especially as stove gets hot.

OP may not have stove, I just threw it in as an option.

If it's plumbed correctly then two pumps can work perfectly well together. It only pitches when the installation is done incorrectly

beanie10 · 19-06-2015 07:58PM

Imagine a situation where rads/cylinder are hot and stove is hot and oil burner is hot. Thermostat on burner will cut oil off however stove cannot cool down as quickly. I see it time after time where hot water in stove back boiler has no where to go but expand to expansion tank in attic and then overflow.
Has been a regulation for few years now to incorporate an electrical interlock to cut oil burner off when solid fuel pump comes on.

Dtp1979 · 19-06-2015 10:08PM

beanie10 wrote: »

Imagine a situation where rads/cylinder are hot and stove is hot and oil burner is hot. Thermostat on burner will cut oil off however stove cannot cool down as quickly. I see it time after time where hot water in stove back boiler has no where to go but expand to expansion tank in attic and then overflow.
Has been a regulation for few years now to incorporate an electrical interlock to cut oil burner off when solid fuel pump comes on.

What? Please, show me this regulation.
A heating system expands 4 % when fully hot. If it's filling the tank through the expansion then the tank is too small. If it's filling the tank through the vent, ie pitching, then it's plumbed incorrectly

beanie10 · 19-06-2015 10:45PM

Hey, you may be right with the plumbing end, but take it from a REC who has been upgrading heating systems for 2 local authorities over last 6 years that as I described is particularly specified on how a heating system is wired involving an oil burner and solid fuel burner.
Your description of plumbing may be correct in a perfect system but its clear that OP system is not plumbed or wired correctly and more than likely will pitch when 2 heating sources are running simultaneously.

Dtp1979 · 19-06-2015 11:05PM

beanie10 wrote: »

Hey, you may be right with the plumbing end, but take it from a REC who has been upgrading heating systems for 2 local authorities over last 6 years that as I described is particularly specified on how a heating system is wired involving an oil burner and solid fuel burner.
Your description of plumbing may be correct in a perfect system but its clear that OP system is not plumbed or wired correctly and more than likely will pitch when 2 heating sources are running simultaneously.

If I was waiting for a sparks to wire heating system controls correctly I'd be old and grey.
I'm talking about systems that are plumbed correctly therefore there's no need to compensate with controls that won't allow both to run at the same time. Plus, I'd love to see this regulation your talking about

Tony Beetroot · 19-06-2015 11:11PM

Any you tube videos to help the op?

Dtp1979 · 19-06-2015 11:41PM

Tony Beetroot wrote: »

Any you tube videos to help the op?

Not really. Just get a plumber in who understands heating controls

19-06-2015 11:43PM

beanie10 wrote: »

Hey, you may be right with the plumbing end, but take it from a REC who has been upgrading heating systems for 2 local authorities over last 6 years that as I described is particularly specified on how a heating system is wired involving an oil burner and solid fuel burner.
Your description of plumbing may be correct in a perfect system but its clear that OP system is not plumbed or wired correctly and more than likely will pitch when 2 heating sources are running simultaneously.

I love that your a Sparks talking a plumber through the principle of pitching especially a plumber who already understands the wiring requirements of a S-plan;)

beanie10 · 20-06-2015 12:00AM

Unless he is a REC it's illegal for him to touch wiring controls. I have given advise on electrical controls in which I'm trained in and authorised to work on.Gasman you have nothing to contribute to this thread. Your post is pointless so don't lecture me on wiring. You don't need to look too far for regs on boiler interlocking.

20-06-2015 12:00AM

Op if it were me I would want it wired with the extra control in the manor already mentioned, not only to reduce the cost of running the boiler but also to prevent scalding in the event of the boiler thermostat being turned to a very high temperture.

In the event that you can't fit a electric cylinder thermostat I would fit a mechanical thermostat like a cytol valve which will control the temperture of the hot water in the cylinder and may also allow the boiler to achive temperture earlier hopefully reducing wastage.

Wearb · 20-06-2015 12:05AM

beanie10 wrote: »

Unless he is a REC it's illegal for him to touch wiring controls. I have given advise on electrical controls in which I'm trained in and authorised to work on.Gasman you have nothing to contribute to this thread. Your post is pointless so don't lecture me on wiring. You don't need to look too far for regs on boiler interlocking. Anyways I'm done I'll leave you guys to slapping each other on the arse all night.

A reference to those regs would be nice??? I regularly do such work and I always thought I was allowed to do so. Have I missed some new regulation?

Dtp1979 · 20-06-2015 12:08AM

beanie10 wrote: »

Unless he is a REC it's illegal for him to touch wiring controls. I have given advise on electrical controls in which I'm trained in and authorised to work on.Gasman you have nothing to contribute to this thread. Your post is pointless so don't lecture me on wiring. You don't need to look too far for regs on boiler interlocking. Anyways I'm done I'll leave you guys to slapping each other on the arse all night.

I'm not doubting the reg exists. It amuses me that it exists and I'd love to see it that's all. And it's not illegal for me to work on heating controls either

beanie10 · 20-06-2015 12:11AM

Yes check CER website illegal to work on domestic wiring unless you are REC. however you can work on commercial installation at the moment but they are talking about changing that too. Suppose to be heavy fines or possible jail time.

20-06-2015 12:11AM

Wow, why are sparks such hard work?

20-06-2015 12:13AM

beanie10 wrote: »

Yes check CER website illegal to work on domestic wiring unless you are REC. however you can work on commercial installation at the moment but they are talking about changing that too. Suppose to be heavy fines or possible jail time.

Nope, Rgi can work and self certify from the spur out.

Dtp1979 · 20-06-2015 12:18AM

beanie10 wrote: »

Yes check CER website illegal to work on domestic wiring unless you are REC. however you can work on commercial installation at the moment but they are talking about changing that too. Suppose to be heavy fines or possible jail time.

I'm talking about not allowing solid fuel and oil to work at the same time reg

Wearb · 20-06-2015 12:34AM

I am also asking about not being allowed to work on heating controls. Have you a link to that reg? Am I no longer allowed to do the wiring on the system so long as a reci wires from consumer unit to heating spur?

20-06-2015 12:48AM

Wearb wrote: »

I am also asking about not being allowed to work on heating controls. Have you a link to that reg? Am I no longer allowed to do the wiring on the system so long as a reci wires from consumer unit to heating spur?

In fairness lots of Sparks are unaware that another trade can legally wire domestic heating controls.

Wearb · 20-06-2015 01:05AM

Don't be too fair. This forum isn't a place to try and bluff your way through things you don't completely understand.

The regular posters here (on P&H) are very amenable to questions, but likewise, feel the need to protect the casual reader from inaccurate posts masquerading as knowledgable advice.

Tony Beetroot · 20-06-2015 01:08AM

beanie10 wrote: »

Suppose to be heavy fines or possible jail time.

A man went down for 3 life sentences last week for wiring a plug backwards, this electricity is deadly dangerous all these electrons.

Thermmostat just turning off rads, boiler still going?

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