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Nest thermostat

gleneagles
Aspiring Legend
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Nest thermostat

Has anyone got one of those nest thermostats for their central heating system that works via wifi ?

Had one fitted when a new central heating boiler was instaled but am certain it has not been wired up correctly.

Heating comes on with the hot water, the last thing you want on a hot day.

 

Sure it's under guarantee but once you inform them about it what is a reasonable time to wait before taking the matter further

We are born into history and history is born into us.
11 REPLIES 11
harrym1byt
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Re: Nest thermostat

It has obviously been wired wrong, if the radiators are actually getting warm with the water heating is called for. There is thought the possibility that you had a pre-existing fault, does it use a three port valve?

 

Look for pipes forming a T, with an actuator on top -These are notoriously unreliable and set whether heat goes to rads or tank, or both. You shouldn't have to wait anytime at all, get back onto them and insist they sort it out. Even if a pre-existing fault, they should have checked it was performing properly before leaving it after a new boiler install and the Hive.

 

 

TheRoadCrew
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Re: Nest thermostat


@gleneagles wrote:

Has anyone got one of those nest thermostats for their central heating system that works via wifi ?

No, don't have one; if it connects to your WiFi can you change settings with the Nest app?

gleneagles
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Re: Nest thermostat

Unlikely to be the 3 way valve as it was changed at the same time as the boiler 4 months ago, accept it could be faulty but unlikely.

The thermostat works fine if set for heating it comes on and off at the set times, no error messages appear on the thermostat and it responds to the app which can be on your tablet or phone, ie: The heating can be switched on or off from anywhere in the world providing you have a internet connection.

So I am convinced the thermostat itself is working ok and it's down to the wiring.

Have contacted them and it's a' we will get back to you' type of reply.

Not urgent as I can turn all the individual radiators down. but I want it sorting.

We are born into history and history is born into us.
JonoH
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Re: Nest thermostat

I have a Nest, it's amazing its sync'd with my Google home along with my lights and door locks. 

 

When I first got mine I had something similar, it was caused as mentioned earlier by the diverter valve and was a 2 second job to fix Smiley  

 Jono H
 Plusnet Community Manager
ReedRichards
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Re: Nest thermostat

My boiler does one thing or the other.  If the room thermostat demands heat then the boiler comes on and switches the three-way valve to the radiators.  If the thermostat on the hot water tank demands heat then the boiler comes on and switches the 3-way valve to the hot water circuit.  If both thermostats demand heat then it does the hot water first and then switches to heating when the hot water tank reaches temperature.

Some systems place the three way valve in a mid position when both thermostats demand heat; it sounds like you have that type.  But your Nest thermostat is a room thermostat, isn't it?  If the heating comes on when the hot water thermostat is demanding I don't see that can be attributed to a room thermostat problem.   

LifeonMars
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Re: Nest thermostat

I  have a combi with Nest and find it great, so dont understand the Hot water side of things, however

Presume you are actually switching the heat mode to off and not using eco mode.

https://nest.com/uk/support/article/What-is-Off-mode-on-the-Nest-Thermostat

harrym1byt
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Re: Nest thermostat


@gleneagles wrote:

So I am convinced the thermostat itself is working ok and it's down to the wiring.

Have contacted them and it's a' we will get back to you' type of reply.

Not urgent as I can turn all the individual radiators down. but I want it sorting.


Yes, I agree - they have wired it up wrong...

harrym1byt
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Re: Nest thermostat


@ReedRichards wrote:

 

Some systems place the three way valve in a mid position when both thermostats demand heat; it sounds like you have that type.  But your Nest thermostat is a room thermostat, isn't it?  If the heating comes on when the hot water thermostat is demanding I don't see that can be attributed to a room thermostat problem.  


Most heating engineers are not that savvy about the wiring and it all goes to a usually very confused main joint box, where it is easy to get it wrong, so the chances are they have got it confused in there.  

By the sound of it, it is an open vented (header tanks in the loft) heat only boiler, likely a Y plan.

Best to very yourself when the engineer claims to have fixed it, that it does work as intended. You can feel the pipes at the 3 port, to determine where the heat is being directed to by the heat. Usually the leg of the T is the flow from the boiler, then the two arms of the T go to rads and water tank. Set it to call for HW first, check that pipe gets hot, then change it to call for space heating and check that arm gets hot.

On older systems, the circulation pump was turned on and off by the 3 port actuator. Modern boilers control the pump directly, so the pump can be run for a while after there is no further demand for heat from the boiler, so the boiler can be cooled down. It enables the boiler heat exchanger to be cooled down and saves a tiny amount of gas too. Its worth checking the pump behaves like this, to ensure the installer has installed the extra cable necessary to does this part. If not, it may affect the warranty on the boiler. 

There is a Y Plan circuit diagram here - https://www.flameport.com/electric/central_heating/heating_wiring_Y_plan.cs4

It is not much different if a Hive has been fitted.

 

harrym1byt
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Re: Nest thermostat

On the subject of three port valves, I have had one of these installed for the past 40 years a spring return type. The spring return type actuator are a notoriously unreliable type - The motor is powered almost all of the time the heating is in use, heat jams the mechanism, the motors burn out. So unreliable I always keep/kept a spare ready to fit. They might last a season, or three, then fail. 

I had a new boiler fitted a few weeks ago and studied the 3-port actuator and found there was a much better design, which was an electrical straight swap for the spring return type. It uses a Sunvic SDM 1901 actuator, entirely motor driven, no troublesome springs and the motor only runs when the valve needs to be moved, which also saves a few watts of power. The actual valve needed to be changed, to suit the new actuator. Of course, I bought a spare actuator - just in case 🙂

gleneagles
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Re: Nest thermostat

Thanks for all your replies.

I fully agree those 3 way valves are a pain, I found it was necessary to replace the motor every 3 to 4 years.

I used the sunvic ones and most had a small lever or control wheel which allowed you to turn the valve manually if it got stuck when the motor was failing but I note this new one which has been fitted does not have a makers name on it or anything to allow you to control it manually.

With the sunvic you could actually hear the motor turning the valve as you switched the heating on and off so when this chap comes to look at it I will have a listen to the valve, assuming of course he does come.

There is a list of Nest installers across the country, one I contacted locally was too busy to even take on more work, the next one was unwilling to do anything even though I was willing to pay to get it sorted, as he said the boiler and other work has cost you a lot of money, it's under warranty so why should you pay out even more.

I also expect a lot of electricians would be reluctant to sort out someone's elses problem.

So will give them 14 days to get in touch after which time I guess it's further action on my part any advice on that issue would be appreciated.

We are born into history and history is born into us.
harrym1byt
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Re: Nest thermostat

The actuator I mentioned has no lever to operate it manually, well the lever was only intended to move a 3-port to the mid position, to allow the system to be easily bled/purged. It just has a red wheel which only indicates with a flat when it is in the mid-position, or actually moving. It only rotates the valve in one direction, rather than the back and forth of the earlier type actuator, no spring involved, so the whole unit is much less stressed. It just rotates clockwise until it finds the required setting, then stops there until there is a different heating demand and needs to move again.

If the installer fails to return to sort it out - An easy way to prevent it heating the radiators, is to take the actuator off the valve then turn the brass D spigot to only allow the heated water through to your HW tank. The actuator will be fixed by just a couple of 6mm screws, so easy to remove/refit.

Beyond that, I would give the original installer a week to give a satisfactory response to you complaint made in writing, then get some quotes to fix it, then write again to advise him/her that you intend to claim the cost of the fix back from him/her.

Hopefully, you paid by credit card? They might be able to help..

You should begin by logging any calls, any letters sent and emails. If still no progress, get someone in to fix it. Send them the bill for the fix cost. If still no response, send 'a letter before action' indicating they have 14 days to refund the cost of the fix, then take out a claim via the small claims court, it is not expensive.