Vailliant sustain 418 heat only problem

[diycooper]

I have just got a new vailliant sustain 418 installed to replace old icons.

Prior to install heating and hot water working. Had new 3 port valve last oct. And had full system power flush 4 months ago and inhibitor added.

New boilor in and wired by engineer. Boilor calls for heat and this works.

When turn hot water on there 240v at boilor but the boilor does not fire up.

Engineer does not know what it is.

Any idea ?

 

[Mottie]

Have they removed the 24v link? I had problems with mine on the day of the install. Vaillant boilers are set up to use Vaillant controls that run on 24 volts. If you use other equipment, you just have to remove the 24v link from the circuit board.

 

[diycooper]

Have they removed the 24v link? I had problems with mine on the day of the install. Vaillant boilers are set up to use Vaillant controls that run on 24 volts. If you use other equipment, you just have to remove the 24v link from the circuit board.

Not sure if the link was left in would heating work but not hot water off controls

 

[Mottie]

Not sure if the link was left in would heating work but not hot water off controls

Mine was all over the place. Heating worked, hot water just kept running - on the first night I had to pull the fuse for the boiler and turn the gas off. Vaillant told me what it was so I sorted it myself while waiting for the 'engineer' to call me back in the morning. Vaillant technical line said it was VERY common!

 

[diycooper]

Have they removed the 24v link? I had problems with mine on the day of the install. Vaillant boilers are set up to use Vaillant controls that run on 24 volts. If you use other equipment, you just have to remove the 24v link from the circuit board.

Not sure if the link was left in would heating work but not hot water off con

Mine was all over the place. Heating worked, hot water just kept running - on the first night I had to pull the fuse for the boiler and turn the gas off. Vaillant told me what it was so I sorted it myself while waiting for the 'engineer' to call me back in the morning. Vaillant technical line said it was VERY common!

Thanks. I did ask him.did he take the bridge out yesterday he said yes. But ive just sent him.vailliant diagram with the 24volt link and asked him.did he remove that exact link.

 

[Mottie]

Not sure if the link was left in would heating work but not hot water off con

Thanks. I did ask him.did he take the bridge out yesterday he said yes. But ive just sent him.vailliant diagram with the 24volt link and asked him.did he remove that exact link.

After my experience, I have mentioned it to a few people on here with Vaillant problems and on a few occasions, I have been right. Even a blind squirrel will did up a nut now and then!

 

[diycooper]

After my experience, I have mentioned it to a few people on here with Vaillant problems and on a few occasions, I have been right. Even a blind squirrel will did up a nut now and then!

Ha ha. I hope it is just the link. Thanks

 

[CountryFan]

I doubt it’s the link, usually just for heating. Either wired up wrong, fault with programmer or cylinder thermostat.

 

[diycooper]

I doubt it’s the link, usually just for heating. Either wired up wrong, fault with programmer or cylinder thermostat.

Thing is everything was working on old boilor prior to install..

Controls pretty new and thermostst on cylinder less than year old.

Can you explain what you mean by doubt its the link usually just for heating ?

Thanks for helping

 

[CountryFan]

Thing is everything was working on old boilor prior to install..

Controls pretty new and thermostst on cylinder less than year old.

Ok. Make sure the cylinder is calling for heat.

Can you explain what you mean by doubt its the link usually just for heating ?

Thanks for helping

When the boiler comes from the factory a link is in place at the pcb until Heating controls are wired in. I forgot yours is heat only, so the heating side is used for the hot water, however, If the link was in place, then the boiler would be attempting at firing all the time, if not firing all the time.

 

[diycooper]

Ok. Make sure the cylinder is calling for heat.

When the boiler comes from the factory a link is in place at the pcb until Heating controls are wired in. I forgot yours is heat only, so the heating side is used for the hot water, however, If the link was in place, then the boiler would be attempting at firing all the time, if not firing all the time.

Thanks

Engineer just confirmed link is out

 

[diycooper]

JUst spoke with installer he said 24 volt links out and heating and hot water are staying on both not turning off.

Am I understanding he should check 240 v across rt and neutral with heating on then hot water to see if the live is switching.

As if staying on liveva constant xall this could be permanent live from y plan or fault on vailliant side.

I cannot understand there to be a permsnent live from y plan as old boilor eorked fine switching both hw and ch on controls.

 

[Mottie]

New boilor in and wired by engineer.

Get him back. Unless there’s a fault with the brand new boiler, it’s something he has (or hasn’t) done.

 

[diycooper]

Get him back. Unless there’s a fault with the brand new boiler, it’s something he has (or hasn’t) done.

im not sure he is up on diagnosing wiring it seems . Bit of a frustration now .

 

[CountryFan]

JUst spoke with installer he said 24 volt links out and heating and hot water are staying on both not turning off.

Well, that's odd, because originally boiler would not fire for hot water. Can you post a photo of the pcb wiring and the front of the boiler? As per @Mottie - It should be your installer sorting, not you.