Pipe stat fitted...but

jilldee · 16 Feb 2009

Posted in Jan, as heating kept coming on in the night. Boiler in loft with a frost stat, set at 5C.

I had a pipe stat fitted a week ago, set at 25C. My heating still comes on in the night, I think for about 15mins, but can't be sure as I'm half asleep. I do know that all my rads heat up.

However, worse than that. Now when my (timed) hot water comes on, so does my heating, even though it isn't set to come on.

My fitter said that he has fitted the pipe stat correctly. He said that I have a 3 port and he has wired it to the white wire.

1) How long should the heating be on in the middle of the night? I though it should just be for a couple of mins.
2) Has my fitter wired the pipe stat correctly?

Any help would be good. Thanks

swbjackson · 16 Feb 2009

Have a look at http://www.honeywelluk.com/lib/pdf/Wiring-Guide-Issue-14.pdf page 28.

Pipe stat should be set to 10, you only want it to stop the pipes freezing.

jilldee · 16 Feb 2009

swbjackson, thanks for your reply. I have looked at the wiring guide p28 as you suggested, but I can't see where it say's to set the pipe stat to 10C. I will try it.

But what about my heating coming on at the same time as my hot water, even though the heating isn't programmed to come on. I guess I didn't make this question prominent in my first post, but it's costing me money in gas.

Thanks

Jonnie · 17 Feb 2009

Is the pipe stat fitted on the flow or return, if on return all the rads will heat up until return water reaches set temp.

D_Hailsham · 18 Feb 2009

swbjackson said:
Pipe stat should be set to 10, you only want it to stop the pipes freezing.

The OP has two stats in her loft; a frost stat and a pipe stat. The frost stat closes as the temperature in the loft falls; the pipe stat opens as the temperature rises. These two stats are wired in series, so they will only light the boiler if the air temperature is below the frost stat setting and the water temp in the pipe is below the setting on the pipe stat.

If the boiler is coming on in the night, the air temperature must have dropped below 5C. It will run until either the air temp rises above 5C or the water temp reaches 25C.

The OP can either turn the frost stat down, say to 4C, so it does not kick in so often, or turn the pipe stat down so the boiler does not run so long. The danger of that is that the water will not get hot enough to have any effect on the air temperature, so the frost sat will be trying to turn the boiler on but will be prevented by the pipe stat.

Wiring the stats to the valve white wire makes sense if your aim is to prevent the house freezing, as it will open the radiator circuit of the mid-position valve. But when the purpose is just to prevent pipes freezing in the loft, the connection should be made to the boiler terminal. In this case the water will just go through the coil in the cylinder, making the Hot Water slightly hotter.

jilldee · 19 Feb 2009

D_Hailsham. Thanks for your reply.

I know nothing about this and neither does the bloke that I have paid £90 to come round and fit my pipe stat!!

He came back 2nite and checked his wiring. The Honeywell help-line said he should have connected to the yellow wire, but there isn't a yellow wire. Instead he re-did the connection to the white wire and put my hot water on. My heating didn't come on, so maybe the problem has been solved. I will only know tomorrow, when my hot water comes on and hopefully not my heating!

Wiring the stats to the valve white wire makes sense if your aim is to prevent the house freezing, as it will open the radiator circuit of the mid-position valve. But when the purpose is just to prevent pipes freezing in the loft, the connection should be made to the boiler terminal. In this case the water will just go through the coil in the cylinder, making the Hot Water slightly hotter.[/color][/size]

Re your above paragraph. Am I just trying to prevent the house from freezing, or the pipes from feezing. The latter I would think. If so, how does my man just connect to the boiler terminal?

D_Hailsham · 19 Feb 2009

jilldee said:
I know nothing about this and neither does the bloke that I have paid £90 to come round and fit my pipe stat!!

Not your fault, but it's inexcusable for the installer not to know what he is doing!

The Honeywell help-line said he should have connected to the yellow wire, but there isn't a yellow wire. Instead he re-did the connection to the white wire and put my hot water on.

He should have asked them: which yellow wire? Don't see how remaking the connection would help. The white wire is for the central heating - not the water - unless there is a problem with your mid position valve.

Am I just trying to prevent the house from freezing, or the pipes from freezing. The latter I would think. If so, how does my man just connect to the boiler terminal?

If the stats are in the loft with the boiler, I would presume that the are there to stop the pipes in the loft freezing; I doubt if the house would get that cold over night.

If the installer does not know how to connect up, he should not be doing the job! But, so you know, he should connect to the same terminal as the orange wire.

kevindgas · 19 Feb 2009

D_Hailsham";p="1144646 said:
jilldee said:

If the installer does not know how to connect up, he should not be doing the job! But, so you know, he should connect to the same terminal as the orange wire.

Click to expand...

some engineers have the nasty habit of using the white & orange wires the wrong way round just to confuse everyone! white should be power in to the 3 port valve microswitch and orange switched power from the valve to the boiler &/or the pump
frost/pipe stats should be wired so as to provide power to boiler & pump bypassing the timeclock, cylinder & room thermostats

D_Hailsham · 19 Feb 2009

kevindgas said:
some engineers have the nasty habit of using the white & orange wires the wrong way round just to confuse everyone!

Now you will have the OP really confused and worried.

Don't see how a mid-pos valve would work wired like that!

frost/pipe stats should be wired so as to provide power to boiler & pump bypassing the timeclock, cylinder & room thermostats

Agreed. The installer seems to have got it partly right as the boiler does come on overnight; it's just the switched live which is wrongly connected.

jilldee · 20 Feb 2009

Thanks for everyones help.

I must confess, it is a little confusing, but I am I right in saying that if the stat is wired to the orange wire, this will just heat the pipes to stop them freezing and my rads won't come on.

D_Hailsham · 21 Feb 2009

jilldee said:
I am I right in saying that if the stat is wired to the orange wire, this will just heat the pipes to stop them freezing and my rads won't come on.

Without going into a long technical explanation, the rads may still come on. It all depends on which was being heated, rads or hot water, when your timer turns the system off at night. If just the heating is on, the valve will stay in the heating position, so the rads will get hot. But if the Hot water was being heated, the rads will not get hot.

jilldee · 24 Feb 2009

A quick post as my fitter is coming 2nite.

I think i understand what u r saying. My hot water is obviously off at night, but my heating is left on, with my room stat set at 15C. I think all that is required is to keep my pipes from freezing in the loft.

I think the frost stat keeps the boiler from freezing, which also stops the pipes from freezing. The pipe stat is there to over=ride the frost stat, so that when the water in the pipes is hot enough everything will shut off and not be on for hours.

Therefore

[/quote]white should be power in to the 3 port valve microswitch and orange switched power from the valve to the boiler &/or the pump
frost/pipe stats should be wired so as to provide power to boiler & pump bypassing the timeclock, cylinder & room thermostats

That being correct, what does "switched live" mean and if I give this info to my fitter will he know what colour wire or number, to connect the pipe stat to in the terminal box?

I guess if he doesn't, i'm just going to have to cut my loses and get someone else in.

Thanks.

Aquaheat · 24 Feb 2009

I guess if he doesn't, i'm just going to have to cut my loses and get someone else in.

If i came to your job (and i'm guessing that many enginners will agree with me on here);

You needed a pipe stat so he should be paid for that, as long as it is left on site.

He has not been able to do the work that you asked him to do so therefore should not be paid for it.

The £90 was to supply and fit a pipe stat and ensure all is working.

If there is a job that i cannot do then i either be honest in the first place and recommend someone else or if i am truly stumped then it is a no fix no fee basis.

If, for arguments sake, he fitted an entire new heating system but could not get it to work would you pay him for the full job?

D_Hailsham · 24 Feb 2009

jilldee said:
My hot water is obviously off at night, but my heating is left on, with my room stat set at 15C. I think all that is required is to keep my pipes from freezing in the loft.

I think that is the first time you have said anything about keeping your room stat set at 15C overnight. I have always assumed that your heating was turned off overnight. Do you keep the heating at 15C overnight because you don't want to feel cold in the night or to prevent the pipes freezing?

I think the frost stat keeps the boiler from freezing, which also stops the pipes from freezing. The pipe stat is there to over-ride the frost stat, so that when the water in the pipes is hot enough everything will shut off and not be on for hours.

Got it in one!

white should be power in to the 3 port valve microswitch and orange switched power from the valve to the boiler &/or the pump
frost/pipe stats should be wired so as to provide power to boiler & pump bypassing the timeclock, cylinder & room thermostats

Click to expand...

That being correct, what does "switched live" mean and if I give this info to my fitter will he know what colour wire or number, to connect the pipe stat to in the terminal box?

The info you have quoted is irrelevant to your situation.

As to what "switched live" means, think of a light switch. One terminal of the switch is permanently connected to the 240v supply, i.e live; the other terminal is dead (0V) when the switch is off. But when the switch is turned on the second terminal becomes live. That terminal is the "switched live", so called because it only becomes live when switched on.

You "installer" should connect the two stats as in this diagram:

Frost Stat

D_Hailsham
24 Feb 2009
1

Wiring Frost and Pipe Stats

jilldee · 24 Feb 2009

I keep the heating set at 15C at night because I was told that it was cheaper than having it timed to come on and off. If thats not correct, I will set it to come on and off. i'm just watching my pennies.

Thanks for the diagram, I will show it to my bloke and if he can't follow it then I'll get someone else. He only fits combi boilers and rads and did admit that he hadn't fitted a pipe stat before, but thought he should learn!!!

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Pipe stat fitted...but

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