Ideal mini c28 ch fine hot water not???

[yplumb]

Can anyone help with this mystery ive asked many paople and nobody upon nobody knows what it is.

boiler works fine for c/h
Hot water the pin does not come out far enough to hit the microswitch whuch makes the boiler fire doen all the usuals

diaphragm ok in pump proving switch
auto bypass ok not permananently open
pump cant be stopped with scredriver.

baffling me only thing i can think is plate to plate but even had that off and water flows through it ok??

anybody who has had this problem pls pls enlighten me to the answer.

like is say ok on ch pin stops about 2 mil short on hot water

 

[Agile]

Have you taken the pump head OFF to inspect the impeller for dirt?

Post back the results !

Tony

 

[yplumb]

yeah took the pump apart was dirty but nothing massive gave it a wipe around housing etc

pump is still strong aswell cant stop it with a driver

took out filter on dhw at same time pretty much had that whole side of the boiler out.

it's had a new diverter put in as the guy informed me that it wouldn't fire up for centrl heating first thing on the morning so they had to fill it up via filling loop and as it was filiing then try to fire boiler up and then it would fire once the pressure was upto about 2.5. and the boiler had warmed up.

re-pressure the expansion vessel and had the prv changed and the diverter valve

so half way there and now i'm stuck on this hot water problem

 

[Agile]

I have only now realised that this is a trade enquiry which is better posted in the CC part of the site!

If you are quite sure that the eye of the impeller was clear then you should open the system flow switch cover and check that the hollow screw on the left is fully screwed in.

Test and advise and join the CC so that you can ask future trade questions there.

Tony

 

[transam]

I have had a similar problem , on some biasi(mini c) boilers but on the central heating side of the boiler , e.g the flow switch will not make on C.H , in particular if a 2nd pump is installed or the boiler is connected to a fill tank as opposed to filling from the mains ,(low pressure) all of these scenarios can have an adverse effect on the primary flow switch , its a differential flow switch , does your boiler work on hot water o.k if you turn off one of the isolating valves on the boiler??

 

[Garfeild]

You could try a new pump,the existing one may be slow.Worst case may be main hex restricted.

 

[Agile]

Unlikely to be running slow if the torque is good as he says. The optical tacho would measure the speed though.

This is a little difficult for me to give an explanation for this but if you add a second pump on the flow the switch does not activate.

If you add a second pump on the return then its OK.

Of course a second pump is not needed in any normal senario.

Tony

 

[transam]

As a matter of interest a J.C Biasi u.k technical desk states that you cannot put a 2nd pump on these boilers , not that I ever took any notice of him .
the same scenario can occur if the boiler is running at a low pressure ,e.g 0.3 of a bar or lower , I must admit I have not come across this prob on H.Water , if the pump , & flow switch are o.k ?However I have got over this prob on several occasions , but it would require alteration to a particular part ,I assume that the primary flow switch pin does come out but not enough??

 

[yplumb]

So Still on with this problem scoured the internet and found people who have had the same problem but nobody with a answer.

ideal/biasi which ever actually suggested bending the microswitch or putting a washer on the end of the pin as

yes the pin does come out when you turn a hot tap on but it sadly stops short by about 2mm of making that coonnection on the microswitch

Just to clarify it works fine on the c/h side

is there anything that I'm missing because ive been thinking about it to long is there something really simple it could be??

shall we try new plate to plate ??
new pump?? but surely if it was the pump it wouldnt fire on ch?
pls forum somebody give me summit i havent already tried

 

[yplumb]

going to turn off one of the ch valves and see if it fires for hot water.

if this wiorks what iis the cure?

before the diverter was changed this was the only way that the central heating would fire by near enough closing off halfway the valve on the left of boiler cant remember if its flow or return, then the pin would come out enough to make the switch

if you never did this the pin would stop short like it does now on the hot water side.

so new diverter and c/h side perfect hot water not??