Boiler Problems, spiking pressure

[shriram]

I have a 'Vokera Unica HE High efficiency combi boiler' which was working fine until this morning.

When I got back home this evening, the boiler pressure was at 0 bar, and the hot water wouldn't work.

I switched off the boiler, and managed to get the pressure back to 1 bar with the filling loop. However, when first turning on the water, the water was hot, but the pressure increased rapidly past 3 bar even, and some safety switched and again the pressure dropped and the water went cold. I reset again, and turned hot water on only (before both hot water and central heating were on). This time, the pressure seems stable at 1 bar and the water is fine.

What could have been the problem? Is it safe to switch back to central heating and hot water? Do I need to contact a gas engineer?

 

[SJB060685]

You need a gas Safe registered engineer. The problem is an easy fix.

 

[shriram]

You need a gas Safe registered engineer. The problem is an easy fix.

OK sounds good, out of interest what is wrong? Is it something I'd done?

 

[SJB060685]

No it's not something you've done. It's a common problem but I will not say what incase you decide to get ambitious.

 

[shriram]

No it's not something you've done. It's a common problem but I will not say what incase you decide to get ambitious.

Hahaha if its dangerous I won't touch it, but I'm just a curious engineering student lol - whats the issue?

 

[SJB060685]

You have an excess pressure issue, that's all you're getting from me. Please please please do not fiddle, you will be breaking the law and potentially putting yours and any loved ones at risk.

 

[shriram]

You have an excess pressure issue, that's all you're getting from me. Please please please do not fiddle, you will be breaking the law and potentially putting yours and any loved ones at risk.

Ok sure, well thanks, I'll call someone in the morning.

 

[shriram]

You have an excess pressure issue, that's all you're getting from me. Please please please do not fiddle, you will be breaking the law and potentially putting yours and any loved ones at risk.

Also one other question, is it safe right now? Can I use hot water in the time being, or should I just fully switch off the boiler?

 

[SJB060685]

The boiler safety controls mean it should be safe but running the burner is only going to exasperate the problem.

 

[Colin H]

Hello, I have the exact same issue as the original poster which resulted in a burst expansion unit inside a new 4 year old boiler. A 2nd expansion unit was added 6 months ago which has also just burst. Can you tell me what the issue is so I can inform the service engineer? Thanks

 

[Timmy D]

Hello, I have the exact same issue as the original poster which resulted in a burst expansion unit inside a new 4 year old boiler. A 2nd expansion unit was added 6 months ago which has also just burst. Can you tell me what the issue is so I can inform the service engineer? Thanks

They shouldn’t be “bursting” like you’re describing.

You may have a heating water quality issue (powerflush/magnet/etc). Or it could be filling/pressure/pipework/safety issue.

Tell the engineer you’ve had two go and a competent engineer should be able to diagnose the fault.