Remeha Avanta boiler losing pressure

[ross37]

I am a homeowner and have a Remeha Avanta boiler plus which loose pressure on a very cold / freezing night. It does not always go to zero but low enough to stop the boiler starting until additional water is added to raise the pressure.

I experience this problem last winter and focused on leaks around the house and followed directions from the engineer. The boiler has worked successfully since last winter, the pressure was ok yesterday, but on our first cold night the pressure has dropped.

When looking at the boiler to top up the pressure there was drips of water around the flow pipe” nipple “from the boiler

Any direction would be appreciated to determine a boiler issue or a potential leak on the pipes which is not obvious

 

[terryplumb]

Any signs of water dripping from the PRV pipework ?( copper pipe outside the premises usually)

 

[ross37]

Hi
Thanks for reading the post
There is nothing ovious the pipe appear ( copper pipe venting through the outside wall)dry however the condensate drain looks wet as if the water may have passed down there

 

[terryplumb]

The leak that you mentioned could be your problem ,or part of it.
The cold night / outside temp ,will not cause a pressure drop on a sealed system. When was the boiler last serviced and the EV,s pressure checked in particular ?

 

[ross37]

It is serviced annually but missed this year (August) as the engineer was sure that the problem was in the pipework but l had my doubts as tracked this problem all last winter
Can you expand on EV's pressure as l don't know of that term. If this means the expansion vessel it was was replaced approx 2/3 years ago under warranty. I think it was was checked last year

 

[terryplumb]

EV = Expansion Vessel. When boiler is working ,central heating in use ,the water in your system expands when its heated. The higher the water temperature ,the greater the expansion.
As your system is sealed and pressurised to around 1 bar when cold ,the pressure increases in the system when water expands. The EV accommodates this expansion ,its basically a metal vessel with a membrane internally splitting it into two halves. One half open to systems water ,other half pressurised with air . Its that pressure that should be checked / recharged if need be.

 

[ross37]

Many thanks for the explanation. I have looked at my paperwork and it was replaced around March 16 under warranty. I will have the pressue checked just don't want the issues of last winter

 

[Jezclayton]

OK So I am coming at this a bit late, but The OP could be enduring a winter of hell or alternatively a future punter may come perusing.

Like many heating engineers, I installed a Remeha Avanta Plus 35c in my property 10 years ago and on the whole it has provided excellent service. In fact I should be ashamed to admit that I haven't so much as had the front off it in the last eight years. After all, I detest working on my own house when I could be working elsewhere and being paid for it? Anyhow, it has developed a bit of a leak of late, much along the lines described by the OP. My wife having got fed up with topping up the pressure every morning for the last 10 weeks, finally demanded I take a look.

Upon initial inspection, there was a fair puddling of water around the internals of the case which was leaking out of the boiler. More embarrassing were the two full buckets of water underneath which my wife had strategically placed to protect her tumble dryer. God bless. Initially expecting a corroded secondary heat exchanger or bleeding auto air vent, close inspection revealed the right hydro block (diverter valve assembly) to be the culprit, in particular where the diverter actuator motor plugs into the diverter head. Since this is not immediately obvious (the unit hides behind the pump) and the seals are well past their prime it is likely that similar leakage will be found on other Avanta models of this age. Since the diverter is put to more use during the winter months it is not unreasonable to expect a greater pressure loss during this period.

The solution was simply to install a replacement diverter valve cartridge obtained for less than £15. The alternative was a replacement hydro block at the not inconsiderable sum of £150 plus. Whilst working on the boiler, I did contemplate a service, however the cost of the service kits (£100 for little more than a seal and electrode) is to my mind money that can be better spent elsewhere. They didn't cost anywhere near as much when Broag-Remeha were located just down the road from me and parts could be obtained across the counter. I did take combustion readings (is that a service these days) which were excellent. Not one service in 8 years and a ratio of 0.0003. I can't imagine a WB or other boiler with an aluminium HE would fair so well.

 

[ross37]

Many thanks for your input
I belive l have solved my problem fingers crossed
I found a checkvalve was leaking when the weather was freezing outside
The valve was under my kitchen cabinets and the leak was not obvious until
l check under the cabinet on the stone floor