Unvented Cylinder with Combi Boiler help

[Ambidexrous]

Hi All,

I'm new here so please be gentle

Ok so here goes - I moved into a new house back in June and was told that the next to last owner lived here with her nephew and had opted to have a vented cylinder installed in order for there to be no contention for hot water when both showers in the house were used at the same time.

The cylinder is backed by a more recently installed combi boiler. I'm not sure what the combi was used to replace, but the resulting setup is now :

Vaillant ecoTEC plus 630

Santon PP2108

Since recently having smart electricity meters installed I've noticed that the vented cylinder is kicking in fairly often, drawing about 3kW for anything from a few seconds to over a couple of minutes.

Is this normal?

Something else I've noticed is that the en suite shower loses pressure when the bath in the same room is being filled, and also when the water for the kitchen sink is run. I thought that the vented cylinder should provide sufficient flow to avoid this?

The Vaillant is set to hear water to 75 degrees, and seems to use a fair bit of gas. In terms of reducing our bills is there anything I can look out for, as according to our supplier we are using more than average and I was under the impression that this kind of setup should be really efficient after the initial outlay!?

Thanks in advance

 

[Dan Robinson]

Since recently having smart electricity meters installed I've noticed that the vented cylinder is kicking in fairly often, drawing about 3kW for anything from a few seconds to over a couple of minutes.

Is this normal?

No - turn the immersion off.

Something else I've noticed is that the en suite shower loses pressure when the bath in the same room is being filled, and also when the water for the kitchen sink is run. I thought that the vented cylinder should provide sufficient flow to avoid this?

Not necessarily - it is dependant on a few things

The Vaillant is set to hear water to 75 degrees, and seems to use a fair bit of gas.

It needs to be around 70 - 75 to heat the cylinder properly. The amount of gas you use is a factor of physics, your hot water usage and the heat loss of hte house.

In terms of reducing our bills is there anything I can look out for,

Without more information it is impossible to say.

 

[muggles]

The cylinder is backed by a more recently installed combi boiler. I'm not sure what the combi was used to replace, but the resulting setup is now :

Vaillant ecoTEC plus 630

That's not a combi boiler - it's a system boiler.

 

[Dan Robinson]

That's not a combi boiler - it's a system boiler.

Spent 15 minutes on the phone yesterday trying to convince someone they didn't have a combi boiler and the problem was with their bloody hot water cylinder. ....very very frustrating.

 

[Ambidexrous]

Ah ok, not sure why I thought it was a combi boiler.

So guys am I right in thinking I just need to turn off the immersion heater?

If so how do I do so? Or would it just be a case of turning the thermostat down on it? Or get some one out to look at it?

Cheers.

 

[snes]

Where the immersion is installed to the cylinder, follow its flex back. It may be simply wired direct to a plug socket - in which case all you have to do is switch the socket off - or it may lead to a timer. If in doubt, take a pic and post back here for more guided advice.

 

[Ambidexrous]

So just for my sanity what are the implications of turning off the immersion heater?

It isn't simply wired to a socket so I've taken a few photos to help. The switch on the wall turns everything off including the boiler.

IMG_5045

• Ambidexrous
• 4 Jan 2017

IMG_5046

• Ambidexrous
• 4 Jan 2017

IMG_5047

• Ambidexrous
• 4 Jan 2017

 

[Roger928]

Deleted.

 

[Roger928]

Something else I've noticed is that the en suite shower loses pressure when the bath in the same room is being filled, and also when the water for the kitchen sink is run. I thought that the vented cylinder should provide sufficient flow to avoid this?

Not necessarily. The flow follows the path of least resistance.
There is a risk of scalding or cold shock from this system just as with any water system when hot and cold supplies are involved..

However!... seemingly you can reduce the risk of "cold shock" occurring if you wear your clothes in the shower.

 

[oldbuffer]

There should be two cables coming from your hot water cylinder.

The thinner of the two will be the connection between the cylinder thermostat and the boiler wiring centre (between boiler and wall switch in picture 2).

The thicker will be the power supply to the immersion heater. Follow the thicker wire to what should be a switched, fused, connection unit (FCU) - NOT the boiler on / off switch. Switch off at the FCU.

The immersion heater need only be used as a back up to give you hot water, but no central heating, in the event of boiler malfunction. It can normally be left switched off.

Also, remember that unvented cylinders and their controls should be serviced annually, as should the boiler.

 

[DP]

Clearly not a proffesional installation.

 

[bernardgreen]

However!... seemingly you can reduce the risk of "cold shock" occurring if you wear your clothes in the shower.

 

[Dan Robinson]

So just for my sanity what are the implications of turning off the immersion heater?

It isn't simply wired to a socket so I've taken a few photos to help. The switch on the wall turns everything off including the boiler.

IMG_5045

• Ambidexrous
• 4 Jan 2017

IMG_5046

• Ambidexrous
• 4 Jan 2017

IMG_5047

• Ambidexrous
• 4 Jan 2017

Jesus that is a terrible installation.

 

[DP]

Jesus that is a terrible installation.

I hope the OP does not need to draw the cylinder

 

[Ambidexrous]

Just thought I'd send an update and thank you all for your comments, some more constructive than others but all in good spirit

After the useful info from old buffer I identified that there was no FCU, so I've wired one in to compliment my wonderful installation (no idea who installed it but it certainly was not me). I'll let you know how I get on, cheers