Indirect Unvented cylinder, Combi Boiler and Nest Thermostat

[Chris1012]

We have just had an indirect unvented cylinder (250l Vertical Telford Tempest) installed along with a nest v3 thermostat.
The plumber was able to modify our existing combi boiler, so it runs like a system boiler.

I am trying to understand how it works as currently the plumber has set it to come on for 2 hours each day (1hour between 5am-6am and 5pm-6pm).
During these times, the boiler remains continuously on and only switches off after the hour mark.
Is this right?
I would have thought during the set times that the boiler should come on, it would work in connection with the cylinders thermostat so once the waters heat got to a set level, the boiler will shut off.

The cylinders booklet states it takes 28min for it to heat up.

Could someone please advise on how this setup should be working and if there is anything I could do to make it more efficient, then it currently is?

Thank you

 

[ShaunCorbs]

Any pictures of the set up ?

 

[Chris1012]

Any pictures of the set up ?

I can take some but the boiler is located in the kitchen and there is shelf above the pipes, so wont be able to see anything and the cylinder in the basement.

 

[Chris1012]

Another potential issue is that it takes 45-60seconds to get hot water from the taps.
The route for the mains water supply enter the kitchen, goes through a water softener then travels 5 meters to the cylinder and then is routed to the rest of the house...

 

[sparkie30]

You are correct the boiler should turn off when cylinder stat satisfied.

Should be wired like this from nest to cyl stat,
Stat to 2 or 3 port valve and then to boiler.

Sounds like plumber has wired straight from nest to boiler thats the reason is on for full hour.

Good luck

 

[Chris1012]

Looks like the gas light comes on the boiler during the schedule to heat the tank but once it reaches the correct temp, the gas light goes off (so does the flame) but the boiler continues to run with the rad light on until the scheduled time is over.
Does this sound right?

Also does the 45sec heat up time to each tap and shower, sound right?
Length to each service is no more than 6meters, using a 22mm flexi pipe

 

[Scott_D]

Pictures needed

 

[Bibbs118]

Combi on an invented, I've scene these sort of installs before and your asking for trouble in my opinion.

If I where you, I'd ring the boiler manufacturers and ask them if their combi can be installed on a invented, I very much doubt they will say yes.

And if they do say yes, ask them to email you a wiring and piping diagram, if they are unable to provide you with a drawing, then, despite the tech help line saying it is "possible", without a drawing it is NOT approved. And probably dangerous.

 

[ShaunCorbs]

Combi on an invented, I've scene these sort of installs before and your asking for trouble in my opinion.

If I where you, I'd ring the boiler manufacturers and ask them if their combi can be installed on a invented, I very much doubt they will say yes.

And if they do say yes, ask them to email you a wiring and piping diagram, if they are unable to provide you with a drawing, then, despite the tech help line saying it is "possible", without a drawing it is NOT approved. And probably dangerous.

Why it's just another heat load prividing you have a draw off eg a tap off the combi your fine

 

[Bibbs118]

Why it's just another heat load prividing you have a draw off eg a tap off the combi your fine

Because without a drawing, it not installed to manufacturers instructions.

Min AR.

Always say on first page, MUST BE INSTALLED TO MANUFACTURERS INSTRUCTIONS.

 

[ShaunCorbs]

Because without a drawing, it not installed to manufacturers instructions.

Min AR.

Always say on first page, MUST BE INSTALLED TO MANUFACTURERS INSTRUCTIONS.

Your joking right nothing to do with gsiur/p

 

[Bibbs118]

Your joking right nothing to do with gsiur

No, if it say, MUST BE INSTALLED TO MANUFACTURERS INSTRUCTIONS, and the manufacturers can't provide INSTRUCTIONS how to install an invented on a combi then you are NOT REPEAT NOT installing it to MIs.

If it says MUST BE INSTALLED TO MANUFACTURERS INSTRUCTIONS unless your bolting a invented cylinder to combi, in that case you can just make it as you go along, or ask your mate how to do it. Then it's fine.

 

[Bibbs118]

Ask yourself this question.

Has it been installed to MIs?

If MIs don't give you INSTRUCTIONS how to do a invented combi install.......Then it's not been installed to MIs has it.

 

[ShaunCorbs]

How is any of that ar

guess they tell you what brand / type of rads to install as well

 

[Bibbs118]

You are correct the boiler should turn off when cylinder stat satisfied.

Should be wired like this from nest to cyl stat,
Stat to 2 or 3 port valve and then to boiler.

Sounds like plumber has wired straight from nest to boiler thats the reason is on for full hour.

Good luck

So thats no temperature control or safety shut off on an invented cylinder!!!! What could possibly go wrong?