Combi Boiler

Jeepers_Creepers

It isn't a catastrophic loss of pressure, so fair chance you can nurse it along for a good while. It isn't a good thing long-term, tho', as the system water will be diluted so the inhibitor in it will have less effect.

3 basic ways for a system to lose pressure. 1 is a leak... Ie water loss from a pipe or radiator, often hidden under the floor. The other is due to a problem with the expansion vessel so that the boiler ejects water out when it expands, and then the pressure is found to be lower when it cools again. And the third is a leaking 'engine'. For that last one, the leak escapes out with the condensate, so is hard to notice.

Slow leaks like yours are harder to trace. A drop in pressure over, say, a day can be ID'ed more easily - eg you can isolate the boiler from the radiator circuit, and see where the leak is - within the boiler, or outwith. But for a leak like yours which isn't really noticeable on a day-to-day basis, it's much harder.

Always worth trying adding a leak sealant? As far as I know, it doesn't have any side effects.

kev2009

ah ok, will bear that in mind thanks, didn't know they did such as thing
In my place there is no under floor as all concrete so the pipe work is all in loft and then comes down the walls.  So plus side is no creaking floor boards, downside is everything goes via loft i.e pipe work, elec cables etc.
The main water supply comes up into kitchen where stop !!!!!! is and then goes up wall etc to where needed.
Property was a new build, 2015.
Kev

Jeepers_Creepers

The good news is, if you had a pipework leak, you'd almost certainly know about it...

Outside your house on the wall near your boiler you'll find a 15mm copper pipe - it'll either be bent back on itself and pointing at the wall, or else it'll be aimed down at the ground, probably over a drain. Found it? Cool. Now fix a small clear plastic bag over it using a rubber band.

See if any water appears over the next few days.

kev2009

Will take a look, the boiler is in a small cupboard in the hall and behind it its the bathroom so it doesn't back on to a exterior wall so I can only assume either the pipe goes through the bathroom, behind sink and bath and then outside OR maybe it's been joined to the pipe work from the sink so it just flows out to the drain? The sink is in a vanity unit and right next to that is the bath so not easy to be able to see much in way of pipe work to trace anything but will see what I can see, without destroying the vanity unit
Will have a look and see if I can see anything over next few days, hopefully it doesn't rain.
Thanks again.
Kev

Jeepers_Creepers

This pipe has to go outside, and it must be visible.

kev2009

Thanks, someone has also suggested I need to add air to the expansion tank? is that a possibility also?
Would need to check manual as don't recall where it said how to add air.
Thanks
Kev

Jeepers_Creepers

kev2009 said:

Thanks, someone has also suggested I need to add air to the expansion tank? is that a possibility also?
Would need to check manual as don't recall where it said how to add air.
Thanks
Kev

That depends on the results of the check I recommended - keep an eye on the pressure gauge as the boiler heats up fully on CH for at least a half hour.

IF the pressure goes up significantly - certainly if it goes over 2 bar - then the most likely cause will be a faulty or discharged EV.

Yes, you can DIY repressure this, and we can guide you through it if it's needed. (Basically depressurise the water side fully, and check the EV air side - it's typically 0.75 - 1.5 bar depending on the model. You obviously need a pressure gauge and a pump - a car or bike tyre one will do.)

jefaz07

Jeepers_Creepers said:

This pipe has to go outside, and it must be visible.

It doesn’t have to go outside. It can go to a condensate pump OR into the waste 

jefaz07

Jeepers_Creepers said:

kev2009 said:

Thanks, someone has also suggested I need to add air to the expansion tank? is that a possibility also?
Would need to check manual as don't recall where it said how to add air.
Thanks
Kev

That depends on the results of the check I recommended - keep an eye on the pressure gauge as the boiler heats up fully on CH for at least a half hour.

IF the pressure goes up significantly - certainly if it goes over 2 bar - then the most likely cause will be a faulty or discharged EV.

Yes, you can DIY repressure this, and we can guide you through it if it's needed. (Basically depressurise the water side fully, and check the EV air side - it's typically 0.75 - 1.5 bar depending on the model. You obviously need a pressure gauge and a pump - a car or bike tyre one will do.)

Here you go again. No he cannot DIY the expansion vessel. It’s behind the case which is not decorative and forms a seal. It forms part of the ‘combustion circuit’ and the OP isn’t allowed to remove it. I have reported this post again and I will continue to do so where you offer advise against the gas regs. 

You offer some great advice in the whole.m, very informative...but there needs to be a limit.  

Jeepers_Creepers

jefaz07 said:

Jeepers_Creepers said:

This pipe has to go outside, and it must be visible.

It doesn’t have to go outside. It can go to a condensate pump OR into the waste 

Thanks Jez - I thought it had to be visible as an indication of summat going wrong.