megaflo issue

[secret squirrel]

Yesterday,

I looked at a megaflo indirect unvented. I have a couple of related questions to it that you kind people will be able to help me with.

First of all, I don't touch these time bombs unless I've got the manual, I now have it because I printed it out from the internet the customer has lost his copy.

The problem is that he has heating but no hotwater and has to heat it directly. He's been doing this for 6 months and has used 1000 yep! 1000 units.

Initially, I though 2 port valve, but I have my doubts, I played with the valve and can hear it moving. (both of them) So, I thinking a thermal cut out. (its never going to be that simple)

My questions are two fold:

First, the 2x two port valves are in the loft eaves on the first floor along with the pump, the megaflo is on the ground floor. In the back of my mind, I only have to drain down below the first floor but I have something niggling away at me. This is the easy part to answer.

Secondly, Normally theres a feed and expansion tank on an open vented system, in this case there is an expansion tank. A pressure gauge all next to the two port valve and pump. I've looked in my book on unvented but can see no reference to it, done some searching on the internet again no luck.

Do I drain down normally? How does this work? can you poke me in the right direction? I know that I need to research this a little and have booked the job for next monday. Please in your replies try and avoid too much terminology......by all means use words containing one sylabul

 

[migoplumber]

you did not say what you want to do.

drain down is same as vented. isolate (soz 3 sylabuls) cold water in. drain.

 

[Jimbob]

The expansion vessel must be for the heating side. The megaflows shouldn't need one as they work with an airgap, due to a diptube in the top. And this controls the expansion.

Sounds like a problem which could be found with a multimeter though

 

[secret squirrel]

Thanks chaps,
I knew I'd forget something,
Yes expansion vessel is for heating side,
Like everything I touch I like to cover all eventualites, so I wanted to know If I drain the system down is it the same and I'd like it confirmed that I do only need to drain the first floor.
I agree I have to play with my multi meter, however, the customer said "if you replace 1 just replace them both" a bit ott for me but that's what he wants.

I would (if possible) someone could explain how an expansion vessel works, I have an idea but can't find information on it anywhere. Not come across one before and would like a little more information

 

[Jimbob]

due to a diptube in the top

i know the answer to this

It has a diptube, which allows it to hold a big airgap. And air (unlike water) can be compressed, which makes room for the expanded water. I dont think i can give a better explaination without a drawing

 

[david williams]

do you have unvented qualifications,if not and things go wrong at time you do job or after, you could face a fine or even worse should you injure someone prison.if you do have relevent qualifications why are you asking such basic questions.

 

[secret squirrel]

Thanks Jimbob,

The mist is slowly clearing.....

David,

Yes, I do have unvented qual. I understand the expansion vessel in the megaflo. However, as requested I have not come across an expansion vessel/tank in the loft before which is attached to a pressure gauge.

As I haven't come across this before, I have booked the job in for next monday to give me time to research this. Unfortunately, I haven't as yet been able to find out any information. Hence my post here, if you can shed any light on this I'd appreciate your input.

 

[david williams]

the expansion vessel in loft should be a sealed central heating system. it may be themal cut out on cylinder has shut motorised valve.check you have current passing through cut out ,then if so is it opening motorised valve.where is boiler could it be a simple airlock.what is hot water themostat on cylinder set at,with boiler on trace heat along pipes till it goes cold ,let me know how you get on. is there a filling loop in loft with expansion vessal and gauge.

 

[davidanth068]

have you tryed opening the 2port valves manualy or taken the covers off to see if they are moving

 

[BLOD]

If the megaflo's about 10 years or older it could have an external expansion vessel.
But from what you've described it does sound like you need to get your multimeter out.

Best of luck