Nest Gen 3 Install advice

[Caoimh1n]

Hi, sorry for another nest installation thread, but I couldn't find my answer in any of the others.

I have recently purchased a new nest thermostat and was looking for a bit of advice.

Basically, I have it wired in and connected to my heating and hot water (I have a hot water tank). When I call for hot water, it works as expected, i.e the boiler kicks in and heats the water. When I call for heat, the boiler again kicks in, however, my problem is that for my heating to work properly, it also needs to call for the hot water at the same time.

I suppose I could put a jumper between the switced live of the heat and water, however this would work both ways and my heating would come on even if I only called for water.

My boiler is a Potterton Promax System HE 24, and I simply replaced manual timers with the heat link.

Does anyone know of a way to have Nest call for heat and water simultaneously when I require heat, and then only call hot water when I request, or schedule, it?

Thanks in advance for any help.

 

[Echo the husky]

It tells you in the instruction manual how to set it to do this. Read the bit about gravity systems.

Edit, I was thinking about Hive! The nest instructions are very poor.

 

[Caoimh1n]

It tells you in the instruction manual how to set it to do this. Read the bit about gravity systems.

Edit, I was thinking about Hive! The nest instructions are very poor.

Ah, thanks Freddo, I though I was going blind as I couldn't see anything about gravity systems in the Nest installation instructions

Would I be right in assuming that this should be possible with the Nest?

 

[Echo the husky]

I would hope so, or it would be pretty useless otherwise. Does your manual mention gravity systems anywhere? I cant seem to find the UK manual online! The Hive website goes into huge technical detail!

 

[Caoimh1n]

This is the installation manual. It does seem pretty basic, and I don't see any mention of gravity systems.

 

[Echo the husky]

Looking here it looks like it's not compatible.

 

[Caoimh1n]

Looking here it looks like it's not compatible.

Thank you for looking Freddo. That looks to be the older version of the Nest thermostat though. The 3rd generation one has hot water control for hot water tanks. It was only released this December.

 

[Echo the husky]

This guy is asking the same question here so it's not just you having problems . I wonder if this feature was forgotten as the nest is a USA design and they have very different hot water systems to the UK.

 

[Echo the husky]

How many connections do you have to the heat link? It should be possible to wire in a relay or 2 to get it to work but it's not ideal. Most UK programmers you just have to install a jumper link or flick a switch on the back or the programmer to make the hot water come on with the heating.

 

[Dan Robinson]

You have not told us what kind of control valves you have on the system, but either way, this is a problem with your wiring efforts.

 

[Caoimh1n]

Thanks Freddo , yeah I was thinking that worst case scenario I could use a Jumper with either a relay or diode to only allow the current to flow in one direction, so the heat would trigger the water but not vice versa.

Currently (outside of the mains to power the link) it's just live and switched live taken directly from the old mechanical timer for heat. The same for the hot water from its old mechanical timer.

 

[Caoimh1n]

You have not told us what kind of control valves you have on the system, but either way, this is a problem with your wiring efforts.

Cheers Dan, it's a Y plan system.

 

[Dan Robinson]

Then wire the system as per page 25.

Not much more to it really.

 

[Echo the husky]

If it's just a y plan there must be a wiring error somewhere, or a fault with the 3 port valve if you need the HW on for the heating to work.

 

[Caoimh1n]

Thanks for the info guys. I'll have another look this evening after work. I'm starting to think I may be wrong about it being a Y system as it's always needed the hot water to be on for the heating to work.

Should I maybe be using the satisfied connection for the water?

Anyway, if I can't get it going this evening, I'll book an installer to do it as I don't want to damage anything.

Thanks again for your advice.