Help With Vaillant Boiler and Immersion Wiring

[brydenn]

Hey Guys,

Hey Guys,

My folks own a hotel in a remote location, they've just had a new heating system installed which needs to be up and running by Tomorrow night for it opening to the public.

Anyway, the electrician who was contracted (by plumber) to do the wiring has a family emergency so can't get to the job for a few days, so I'm going to do the wiring, I'am a qualified electrician but have zero experience with boilers etc as I'm an industrial electrician.

So I was hoping someone with experience could point me in the right direction?

It's a Vaillant ecoTeEC plus boiler with a programmer. There's also two 600/800 ltr cylinders which are connected, each cylinder has 2 thermostats. There aren't any valves.

Cylinders/thermostats. The cylinders are obviously a backup, but from what I understand the the cylinder thermostats need to control the heating?

Whats the correct wiring for this? do I take each thermostat back to the boiler in to RT 24v?

Do I run a supply to each cylinder? or one supply enough as they're connected?

Any help/guidance appreciated

 

[AndyPRK]

Cylinders and no Valves. How's that plumbed then?

2.5mm cable is usually used to connect to the immersion heater in the bottom. A 16a mcb per cylinder.

 

[EFLImpudence]

Is the system UNvented?

 

[Echo the husky]

I have many questions.

 

[brydenn]

Is the system UNvented?

I'm not sure, I'd need to confirm this tomorrow.

I believe it is though from where it's situated.

Thanks for reply

 

[Echo the husky]

Any photos? I can't really see how you can have control without valves. Is the plumbing completed? There are several different versions of the Vaillant Ecotec boiler, which model do you have? For a standard system you would only connect to the X1 terminal block.

 

[brydenn]

Any photos? I can't really see how you can have control without valves. Is the plumbing completed?

I don't have photos but I can remember (most) of the connections from boiler.

Yeah plumbing is complete.

All I was told by plumber was there's no motorised valves. The cylinders are obviously just for backup.

He needs the cylinder thermostats fitted to control temp/boiler

 

[Echo the husky]

Unless I'm being thick, you can't control the temperature in 2 cylinders with one boiler without valves. Unless the boiler only supplies the hot water system and the boiler temperature is set to the water temperature and the boiler shuts off when both cylinder are up to temperature. I've never seen it done like that though. Also isn't there a requirement for unvented cylinders to have a valve controlled by an overheat cutout? If he needs the cylinder thermostats to control the boiler they can't be for backup.

 

[EFLImpudence]

If it is unvented you must be qualified to work on the system.

Where is the plumber? Is he not qualified?

 

[brydenn]

If it is unvented you must be qualified to work on the system.

Where is the plumber? Is he not qualified?

Yeah, he's qualified. He will be there tomorrow.

He doesn't know how to wire them though!

 

[kai]

Cylinders and no Valves. How's that plumbed then?

2.5mm cable is usually used to connect to the immersion heater in the bottom. A 16a mcb per cylinder.

That is basically correct for a 3kw immersion (or lower rating), remember to put at least a 13amp rated Double Pole Switch as a controller for the immersion heater, or even a purpose made immersion controller device.

http://www.timeguard.com/products/t...se-timeswitches/24-hour-fused-spur-timeswitch

 

[Echo the husky]

I imagine for hotel use it will be on continuously, if the boiler isn't providing the heat. The last large cylinders I wired each had 2 6KW single phase elements as backup, should the boiler be out of action. The immersion stats had to control contactors as they were only rated for 16A. The plumbing company who did the install said they usually do the wiring, and apparently connect the backup elements to the stats in the same way as a 3KW heater. I can't see the 16A stats lasting long with a 26A load. They said it was also difficult fitting the 4mm² flex into the thermostats terminals!