Megaflow & Heating fault

[Dan Masey]

My first job monday morning is a fault on a system boiler thats constantly loosing pressure on the heating. The house has an indirect megaflo unvented cylinder. The tenant has to refill the system every morning. All the heating pipework is service mounted everywhere and no sign of any leak whatsoever. However, The tun dish is constantly dripping. Its all on an S plan system, with 2x2port vales. My first thought was that the coil has split inside the cylinder..... but she said the water out the hot tap is very clear and as it should be. No hotter than usual. The water from the tundish is also clear.

Any other ideas before i go there???

 

[Whn1]

Does the pressure relief from the boiler run into the discharge before the tundish? Seen this a couple times.

if the coil split the water would probably enter the heating system rather than exit it.

 

[vern]

What Tony said if the coil had gone it would be at 3 bar and so would the heating be, as it would just bleed off pressure from cyl.....

my guess heating expansion is depleted and heating PRV is teed off into PRV on megaflo cyl,

 

[Dan Masey]

Nope the PRV on the boiler never lets off. Thats what i thought mate, the pressure in the heating wouldn't be enough to push out the coil causing the TPRV on the cylinder to let by......

 

[Whn1]

Any work been done recently?

 

[vern]

Well air gap wants re charge on megaflo and do a check maybe got a leaking hex, what's the boiler?

 

[Whn1]

Good point vern, check the condense line.

 

[vern]

Good point vern, check the condense line.

I am assuming its condensing Tony for that fault though?

 

[Dan Masey]

thats what i need to check.I think the boiler is in the kitchen downstairs and the cylinder upstairs. Another lad i work with has looked an is adamant its the coil. Could i cap off the primarys for 1 day and see if it happens still?

 

[plumber0808]

has the filling loop been left on? Might be slightly passing, over pressurises let's off and repeats the process.

 

[vern]

Won't be coil ....deffo not, if it was, its covered under 25 year warranty if registered and fitted correctly....

 

[Dan Masey]

has the filling loop been left on? Might be slightly passing, over pressurises let's off and repeats the process.

Tenant is saying that each morning she takes the pressure up to 1.5 bar ish.... then throughout the day its gradually drops to 0. But she see's no sign of leaks outside on the blow off pipe and condensate pipe is under the sink into the trap so haven't checked that yet.

 

[plumber0808]

Tenant is saying that each morning she takes the pressure up to 1.5 bar ish.... then in the morning its at 0.

If its not that I would then look at the expansion vessel. If that's fine it might be that the prv is faulty or a bit of crud stuck in it allowing it to pass water

 

[Dan Masey]

But both of these faults would mean water discharging through the PRV pipe from the boiler outside right? She did say she hasnt seen anything discharging from this pipe. (she could be wrong i guess) i mean who stands outside all day looking.......

 

[Aquazone]

On an unvented cyl, the pressure would rise in the central heating circuit if the coil is split, as the water in cyl is at mains pressure, as others have said.

Had this last week, my mate was adamant filling loop letting by. Isolated cold feed to cylinder, let pressure out at hot tap and pressure started to drop on CH, showing coil split.

If there's no leak on pipe work / rads, and heating PRV is not blowing off, cracked hex is probs next check?

 

[Whn1]

Process of elimination dan, it'll be one of the things mentioned above, let us know how you get on mate

 

[vern]

But both of these faults would mean water discharging through the PRV pipe from the boiler outside right? She did say she hasnt seen anything discharging from this pipe. (she could be wrong i guess) i mean who stands outside all day looking.......

Boiler then if an early logic system bet the hex has gone?

 

[dad]

I have a Mega Flow system and the hot water is not very hot. It was very hot but now is tepid. Any ideas what the problem might be ?

 

[plumber0808]

I have a Mega Flow system and the hot water is not very hot. It was very hot but now is tepid. Any ideas what the problem might be ?

Might be better starting another thread with a bit more info. Direct or indirect cylinder?

 

[Dan Masey]

cracked HEX??

 

[Aquazone]

Cracked heat exchanger in the boiler. If no obvious drips under boiler, pressurise the CH, turn boiler off, and if condense dripping / running through then you have a crack in heat ex.

added: above assumes that its a condensing boiler.

 

[Dan Masey]

Cracked heat exchanger in the boiler. If no obvious drips under boiler, pressurise the CH, turn boiler off, and if condense dripping / running through then you have a crack in heat ex.

added: above assumes that its a condensing boiler.

Thanks for all the advice. Ill check all these things when i get there and hopefully have an answer. A lot of our houses do have Ideal Logic boilers so its a possibility.

 

[SafeGasInstall]

But both of these faults would mean water discharging through the PRV pipe from the boiler outside right? She did say she hasnt seen anything discharging from this pipe. (she could be wrong i guess) i mean who stands outside all day looking.......

RULE 1
Never ever trust your customers !!!