Who knows about megaflow tanks?

[PlumbingQuandry]

I've had two well-respected local heating engineers around to look at/quote for fixing, my non-functioning central heating.

Heating engineer no.1 tells me that my boiler makes hot water & sends it to the megaflow which stores it.

Heating engineer no.2 tells me that no, the megaflow solely makes the hot water, which it stores & my boiler deals with the heating alone. I'm

If man no.2 is right then that must mean my megaflow is operating as an immersion heater surely? There's no on/off switch for the megaflow. I have a regular system boiler, not a combi. The boiler recently broke down (seems like an electrical fault) but we still had hot water, no heating.

How are these things supposed to function?

Our Megaflo I’m sure just stores the water. I use the boiler timer or over ride to make hot water. There is a separate immersion. If the boiler is out of action we would have hot water by using the immersion.

The megaflow is a storage tank.

Your boiler heats water, then circulates that through a coil inside the megaflow, heating the water stored in there up. The megaflow may also have an immersion heater in it.

The magic is that the megaflow operates at mains pressure, so your hot and cold will come out of othe taps at the same pressure.

I used to have a Megaflow for hot water and heating and no boiler as we had no gas connection

Well I'm completely now...

My mega flow also operates as an immersion in case the boiler breaks down.

Maybe yours is the same and you just haven't found the switch yet? It's not a switch on the tank btw, but a fused switch on the wall of the cupboard it's in.

There are no swiches at all for my tank. That's what's weird. No fused switches whatsoever. The tank is in a room of it's own with blank walls. There is nothing in any of the rooms adjoining either.

Post some photos of the cylinder, and of the pipes and cables around and connected to it.

If you are in the UK and have a gas boiler, it would be abnormal not to have it heat the water in the mega flow.

Hi Piglet, many thanks. Pic attached. It's difficult to get a full picture because the room is so tiny but everything of note is in this pic. There are no pipes/wires etc round the back. It looks to me like the power goes into the floor void somewhere? I have a heating engineer tomorrow who's going to take the floor up and look. The boiler is located in the adjacent cupboard but the only switch in there is power for the boiler which is currently off as the boiler's broken. The tank is still working so it's getting it's power from somewhere else. I'm too embarrassed to tell you who fitted this tank but it was a highly reputable well known company. Seems like they're not all they portrayed themselves as..

Trouble is, if you don't know, you don't know. That's why we hire these people to do a decent job.

I can't read it, but on the square grey plastic cover it should say "heating element" or something similar, and inside should be an immersion heater (sometimes two) and connections. There really should be a switch to turn that on and off, because energy from electricity costs three or four times as much as energy from gas, so you'd only want to turn on the immersion heater when the boiler is out of action. Preferably the switch would have a neon indicator to draw attention when it is turned on. The switch should have a durable label to say what it does. You can buy switches ready-marked, but many electricians now carry a small label-making machine for this kind of job.

If you have solar power or off-peak cheap rate, it may be different.

The two lagged pipes bottom left are the flow and return from the boiler, which normally heats the water. Yours will be similar (possibly not identical) to the layout shown on pages 9 and 19 of this document

The pipe coming out of the top of the cylinder should also be well-lagged as it is hot. The right-hand pipes will normally be cold but you can lag them if there is any risk of frost.

Your tank cupboard looks much nicer than mine! The grey box with the wires... one mine, one goes to / from the immersion switch (labelled beautifully by yours truly). The other one to a box labelled “danger” 😂😂. You must have an immersion switch somewhere.

Ok people, we have pictures Pic one says 'boiler control', pic two says 'element control' & pic 3 is an overall view. Both the small brass thingies have a tiny notch cut into them that points towards (minus) on the dial. My plumber wasn't keen on taking up the floor as the heating miraculously decided to start working. He said it was all working perfectly He also said he thought the megaflow was not being used as an immersion heater but he didn't sound that convincing to me. What do you make of it now you can see the insides? I don't believe there is any switch for this thing. He wanted to know who fitted it and I was too ashamed to say. It was Pimlico Plumbers. This was fitted when my old tank froze/burst in the -15 windchill last winter. (it used to be in an uninsulated eaves cupboard) Do you remember the extreme cold? Everyone's condensate pipes were freezing up. There wasn't a plumber available for love nor money for weeks & I had a house full of oldies at the time. I just needed it done & I was robbed blind for the privilege.

Pics might help...

Might it be the case that this is wired into the timer box, which when it clicks, cues the boiler to start up & then fill the tank that way? Not sure why both these gauges are set to zero. Or the absence of a switch? Is there no external wall switch because these two do the job instead?

If your boiler isnt working but you still have Hot water then it may be that it is heating the water from the immersion heater inside

It would be very unusual to have a boiler to do ch that doesnt do hot water cylinder as well

In some flats there can be a megaflo type tank that only works on the immersion with no gas boiler

From the two wiring plugs one is called boiler which would normally be heat from the boiler and the other is element which is your immersion
The switches may not be set to zero as that could be a slot for a dial
Good old Pimlico they are as bad as Aspect
PM me if you need any help

Have a look in your consumer unit. There will (should) be a 16A breaker labelled "Immersion Heater"

If you look at the speed your electricity meter is spinning or flashing, after you've run a bath, then it might slow when you turn that breaker off.

Just had a look and we have a 16A breaker for the boiler, nothing at all specifically dedicated for the megaflow, so I'll assume they've wired them together on the same one? I've just had a look upstairs. The heating is switched off at the timer box, hot water is on. The boiler is switched off. So I had a look at the electric meter and the dial is rotating once every 7 seconds which seems reasonably rapid. The only electricity being used in the house currently is the large fridge/freezer and the lights in one room. So I think I might conclude the tank is heating by immersion & not from the boiler...

Switching off the boiler breaker had no impact on the speed the electric meter was spinning. So perhaps they aren't wired together. I'm totally I think the engineer needs to take my floor up tomorrow so I can have peace of mind & find out exactly how this set-up is functioning.