HELP!!!! Biasi Combi M90 24S No Pressure

[doitall]

The guy that turned up today was a "Plank" and I hope you make Homeserve aware of the fact.

He was sent out to find a leak, Not only he didn't find one, but he didn't look.

Leaving the boiler isolated would be reasonable knowing a plumber, cough, was calling in the morning to sort it.

Did the boiler pressure drop overnight, if it was isolated, or didn't anyone check

 

[Lizbet30]

The pressure was left at zero which is what it was when the engineer left. I thought I should leave it for today as a plumber was coming this morning. When the plumber came and then told me CH was not working I did not know about the CH valve so just accepted it.

This is totally mad but the pressure is staying stable at the moment or at least for longer than previously - will keep monitoring. Homeserve are going to send out a service engineer from previous company again tomorrow. He is the manager so he is going to check over boiler tomorrow and hopefully definitive answer then. I dont understand why the boiler is relatively stable now if it was having dramatic drops in between the 2nd service engineer visit and yesterday's service engineer visit.

I am going to leave everything off for an hour and then try CH for an hour again and see what happens. After that I will let it cool down and see what happens again. I will then isolate the boiler myself as I know what to do now. Just need to double check do I switch off, CH flow, cold water inlet and CH return all at once and then wait or do I do it in turn? The other thing is I do not seem to have a valve for the dhw outlet is that normal?
Still no evidence of leak anywhere in house. Have gone round and manically checked all rad valves (again) have checked pipes in house again....nothing!! If you could let me know about isolating the boiler that would be great thanks.

 

[doitall]

The second and third pipe from the left are the heating, you don't need to turn anything else off.

Again if the pressure is holding I would leave it as is.

One comment you made earlier about the pressure being 2.2bar so you bled the radiators. It is normal for the pressure to rise as the water heats due to expansion, if you lower it by bleeding the rads then the cold pressure will be lower again.

You should fill the system and bleed all the rads to get the air out, then leave the pressure at 1.2-1.5bar, then not touch anything through its heating cycle.

The question we asked earlier about the high pressure when the system heated was valid, because we wanted to know if the expansion vessel was sound or not, for example if it gets to 3bar it would solve the mystery.

 

[Lizbet30]

The pressure was holding at 1.4 when cold and is still there hour later. I have now turned on CH and it is up to 2.1 but seems stable at the moment. I will keep monitoring it. I am going to run it for an hour then do the flow test. My pipes are different fromt the way you say - from the left are CH flow, DHW, Gas, DCW inlet, CH retun and PRV pipe to outside. I will shut off CH flow and CH return. Should I also shut off the DCW to do the test? Also should I have the CH on or off during this- I am so sorry if this is obvious and should be off.

I am also going to buy a length of pipe tomorrow to test PRV pipe as Tony (agile) suggested. I will have to also borrow ladder to get up to outside first floor. This may take a day or so. However, I am pretty sure it is not that as when it has overflowed before, it discolours the tarmac outside the house. What I thought I might do is put a basin there anyway to see if it catches anything. Thanks for all your help though.

 

[doitall]

Just stretch a balloon over the pipe you will soon know if it drips. A plastic bag or glove will also do, whatever is to hand really, and elastic band will hold it on, unless it fills with water

Whats the flow test

If the pressure isn't dropping I wouldn't touch anything otherwise just the heating pipes

 

[Lizbet30]

Have put a big basin under PRV pipe and used a brick to weight it down. Nothing is coming out though. Will buy a balloon tomorrow. It is just the ladder issue as do not have long enough so will have to see what can do. I meant I will give the CH another hour and see if dropped. If not will leave but I was going to turn off the CH outlet and the CH return to isolate the boiler. I just need to know if I also turn off the DCW supply too. Also do I have the CH on or off? This should tell me if it is boiler problem or leak problem. However, I need to know how many and which pipes to turn off.

 

[doitall]

You only need to turn the two heating pipes off.

Do not use the boiler, so isolate it on the wall electrically.

 

[Agile]

The second and third pipe from the left are the heating, you don't need to turn anything else off.

I dont know what boiler he thinks you have got! ( they are DHW out and Gas respectively! )

Look at MY posting where I told you which valves to turn off.

With the valves OPEN try CH for 30 minutes and see if water comes out of the PRV and pressure falls.

With valves closed, do NOT run CH, just use it for DHW overnight.

Tony

 

[Agile]

At the moment pressure is at 1.5 I turned on CH 30 mins ago after I turned on the valve which had been left closed yesterday by the engineer yesterday. The pressure was as 2.2 and I was starting to get worried so bled the radiator until returned to 1.5 as know that is meant to be correct prssure. !!!!!

You are confusing yourself by tampering!

The starting pressure of 1.5 should go up to about 1.8 when heating is all hot.

Any more like 2.2 indicates the expansion vessel is incorrectly set or failed ( unusual again ). You do NOT test them by seeing if air comes out of the schraeder valve ( unless you are a homeserve muppett! )

A teacher is meant to be an educated person well able to follow instructions to test boilers, cars, computers etc. And to double check their spelling too!

If you have a car foot pump I will tell you how to see if you can fix it yourself.

Tony

 

[Lizbet30]

OK. Will do that. Am running CH now and no pressure drop so far and been nearly an hour. The basin outside is still empty so seems ok.

Don't understand how pressure can now be stable considering I was losing 1.5 to zero pressure in 10-20 mins on Wed! I had to fill up 7 times then!

Regarding closing valves, is it ok for me to do this from say 8pm to 12 pm before I go to bed - are 4 hours enough for test?. The reason is that it will bother me and won't be able to sleep properly.

Do I need to isolate the boiler electrically and if so can I just do that by pulling out the fuse in the consumer unit in my basement (old Wylex fuse box) which only serves the boiler? Otherwise I think the wires go into a plug socket in my cellar so could just pull that out. Would be happier also pulling out fuse though as know def off then. I have checked this before by going around house and checking appliances and lighting etc and def only serves the boiler. Should I also turn of gas valve on boiler when I am doing this? If so is it ok to turn off just at unit or should I also turn off at mains?

 

[Agile]

Dont overthink!

Pressure should have been 1.5 with boiler COLD before you started to use CH.

To turn boiler off just turn right knob to "0" position.

I am going out to Chinese meal now, I hope you can manage until I return!

Tony

 

[doitall]

The second and third pipe from the left are the heating, you don't need to turn anything else off.

I dont know what boiler he thinks you have got! ( they are DHW out and Gas respectively! )

Look at MY posting where I told you which valves to turn off.

With the valves OPEN try CH for 30 minutes and see if water comes out of the PRV and pressure falls.

With valves closed, do NOT run CH, just use it for DHW overnight.

Tony

I'm looking at the manual Tony, you are describing the "Parva M90 24S"

 

[doitall]

The starting pressure of 1.5 should go up to about 1.8 when heating is all hot.

Any more like 2.2 indicates the expansion vessel is incorrectly set or failed ( unusual again ). You do NOT test them by seeing if air comes out of the schraeder valve ( unless you are a homeserve muppett! )

Tony

Not correct Tony, if the expansion vessel is undersized for the system it will quite easily go to 2.2 and more.

If the vessel was duff it would have shot up too 3 bar in minutes of the boiler being on.

The OP would be better doing all these tests with the system cold.

 

[Lizbet30]

Have isolated boiler for more than an hour (CH out and in) the pressure has dropped from 1.4 to just above 1. Will post results just before go to bed. Does this mean that there is no leak and the issue is expansion vessel? Could it be that the system was not totally cool and so could still be leak before I get all excited? Also could the PRV still be at fault even with boiler isolated or does this mean it is ruled out?

 

[doitall]

No Lizbet30

as the water cools the pressure will drop, so you need to pressure the boiler and do the test when everything is cold.

Do me a favour please before you go to bed.

Pressure the boiler to 1.5bar, then turn the cold off and open a hot tap, make sure the boiler is off first. then post back if anything happened