No hot water to taps from Megaflo - outlet pipes are hot.

[GF]

Hi everybody. This is my first post on this forum and I have a problem that I would like advice on;

ysterday we noted that we had no hot water. The boiler starts up when the 'hot water' programme runs but the boiler temperature indicator quickly (15 secs) rises to 70 degrees and the burner light goes out. The pipes on the outlet side of the megaflo unit are hot but the water from the hot taps is cold.

Any ideas?

I have a Heatrae Sadia Megaflo system with a 3 port motorised valve. This is connected to a Baxi System 60 boiler.

Here's hoping.

thanks
Graham

 

[gas4you]

As you have a 3 port valve, you should also have a 2 port valve on the flow pipe to the megaflo.

Check this is open as well when there is a call gor HW from the programmer.

Do we assume that the rads all get hot properly when asked to?

 

[Agile]

"we have no hot water".

As the outlet from the cylinder is hot then we must deduce that NO water flows out of the hot tap ???

In that case the water supply to the cylinder has probably been turned off or the pressure reducing valve has failed ( unusual to do that suddenly ) or the filter has suddenly clogged ( thats unusual too! ).

Anyone working on an unvented has to have a special qualification.

Tony

 

[GF]

Hi Guys.

thanks for the quick replies. There are 2 valves fitted to the magaflo. The 3 port valve is at the bottom and there is a valve above it that has a spring return that can be latched open.

When the hot water tap is turned on the 3 por valve moves to the fill/vent position and moves back when the tap is switched off. The water from the tap is cold despite all of the pipes on the outlet side of the megaflo being hot.

what does the 2 pot valve do?

cheers
Graham

 

[Agile]

Right so you do have water from the taps but its cold!

In that case the hot water connection on the cylinder must also be cold!

All the valves you have described are part of the reheating side of the system and in the boiler circuit.

Manually latching open the two port valve is bypassing a safety device which is both dangerous and illegal!

Tony

 

[GF]

Just checked the valve positions and whether the radiators get hot.

The 2 port valve is in the 'auto' position and the 3 port valve is in the A position.

The boiler did the sam again, quickly showing a temp of 70 is reached then shutting down.

I will follow up any other suggestions or test processes if you have any.

cheers
Graham

 

[Agile]

It sounds as if you have already latched open the two port and that did not allow it to reheat. But it takes about an hour to reheat from cold.

In the auto position the lever does not more far when closed.

The lever moves freely all the way when its powered open.

This valve may not be moving! Either the motor failed or the overheat stat on the cylinder has tripped and needs resetting ( thats unusual though! ).

If it has been connected in the traditional way the "B" port of the three way would go to the two port and the cylinder. It could be that the cylinder stat or control system has a fault.

Tony

 

[GF]

While trying to see what the problem is I have moved the 2 port valve lever to check it moves freely, which it does. Whem moved to the 'open' position (by hand) and released it moves back to the 'auto' position.

At the moment neither of the valves move when the programmer calls fro heat from the boiler.

The pipe directly above the 2 port valve is hot and the pipe below it (into the cylinder) is cold.

cheers
G

 

[Razor900]

Soiunds like the pump isnt working to me, anyone checked?

 

[GF]

is there an easy way to check?

I have a mutimeter so can check the electrical supply.

thanks
G

 

[Agile]

Look in the FAQ on this site for advice on checking pumps!

Tony

 

[GF]

I will check the pump.

What would be the effect of placing the 2 port valve into the Manual position?

NB: is it actually possible that the water in the megaflo tank is hot but that the water which is supplied to the hot water taps is cold (e.g. the water to the taps is bypassing the water heating system?

if this is possible I suppose it points to either a faulty valve or a faulty pump?

'Clutching at straws here'

graham

 

[mickyg]

check the overheat hasn't tripped on the megaflow.

 

[GF]

Thanks.

where is the 'overheat' reset?

NB: I put the 2 port valve into the manual position and latched it. I then ran the boiler for about 15 mins and then (bizarely) hot water came out of the hot taps (so I ran a bath for my wife).

I have put the valve back to 'automatic' and set the programmer to demand hot water but the boiler has not re-ignited.

Arrghh.

Graham

 

[mickyg]

Thanks.

where is the 'overheat' reset?

behind the control cover on the cylinder. Careful as live electrics inside. but should find a red button on a thermostat.