heating system

[paul b b]

hello chaps,

ok, the heating system that is being installed has....

2x megaflows

1x 50-70kw boiler

under floor heating (wet)

it requires 4 pumps...

1 for each mega flow

2 for underfloor heating

1 for bathroom rads

all of the above apart from the manifolds are going to be in a cellar, i thought i would be easer to run a 10mm2 down to a second cu and run cables in conduit.

so here come some questions....

is it ok for the pumps to be run from FCU's? the megaflows and boiler will each have its own circuit.

how many cables can you run in a conduit?

can i take a 16mm2 earth from cu1 to cu2 and bond to oil/water from cu2?

now the complcated bit....

stats... should i run in 3core to be future proof as the plumber said only need 2 core?

he also wants a cut out incase the pressure gets to high. how do i do this?

i amgoing to use a honeywell box, i take it all stats are wired in from there?

the set up

how is this wired in? its made by centerstore

more to follow proberly...

 

[batty]

The connections on right are for tank stat require two core and earth Immersion is wired in butyl three core some recommend 2.5 butyl.

 

[paul b b]

but where does it get its power from?

 

[batty]

Standard spur on seperate circuit.

 

[paul b b]

sorry i was asking what terminals on the megaflow do i use

 

[batty]

For the immersion you mean?

 

[paul b b]

yes, why does it have 1 2 3 earth?

 

[batty]

123 earth is for the tank stat for central heating side you only connect two terminals and earth instructions will tell which terminals are needed. Immersion is wired direct into immmersion terminals that is why you have two flex gripper thingies.

 

[sparkytim]

Hi Paul, nice little job for you.

FIRST YOU MUST DETERMINE WHAT THE SET UP IS LOAD WISE.

The boiler will be supplying the main heat by the look of it, How many Immersion Elements are required to be functional?

As they may be only for BACK UP you may not need anything more then two 20 Amp Radial circuits for Two Immersions and all the other control wiring can come of a 13 Amp FCU.

You will need Zone valves, room thermostats and Programmer(s) to control this system.

I suggest you sit down with the Heating guy and get clear what he is doing and what he wants.

These can be quite complex set ups

 

[ProDave]

What a bizare system.

Those are INDIRECT cylinders, so in theory, the immersions are just for backup and will never be used. So what's going to heat the hot water cylinders then? the 70KW electric boiler? If so that's IMO a stupid way to do it. If you are going to heat them by electricity I would just have bought direct cylinders and used the boiler just for the heating.

As answered before, the thermostats for the immersion heaters are those white things that clip on top of the element. You just connect the supply via FCU, timer or whatever to that, and the other 3 terminals are the cylinder stat that will control the pumps or valves to shut off the heating input when the tank is up to temperature.

If the plumber has asked you for a "cut out incase the pressure gets to high" he's talking from where the sun doesn't shine. The thermostats are the first line of control and stop the heat input once it's up to temperature. That is all that's needed. In addition there are mechanical over pressure and over temperature blow off valves that vent the cylinder if it gets too hot or the pressure builds up. The plumber should know that as he's the one that has to fit them. Is he qualified for pressurised systems?

And where is he going to run the blow of output to? It needs to be piped in copper via the tundish to a drain or soakaway. Bearing in mind it's in a basement, that could be tricky.

What sort of building is this that needs so much hot water? and why does one cylinder have two immersions and the other only one. I'm guessing it's a large building.

EDIT: On re reading, you mention a 50-70KW boiler. I first read that as being an electric boiler, but you wouldn't get an electric boiler that high a rating (work out yourself how many amps it would need)

Instead, I think you mean to 50-70,000 BTU boiler, that thing in the right of the photograph. So that's a gas or oil boiler then, so only minimal load for controls etc.

If that's a gas or oil boiler, then the whole thing makes a lot more sense and indirect cylinders are the correct choice, in which case the immersions are just for backup.

Oh and those are not "megaflows" just some other make of pressurised hot water cylinder. Just like my Dyson vacuum cleaner is not a "hoover"

 

[Apache]

Oh and those are not "megaflows" just some other make of pressurised hot water cylinder. Just like my Dyson vacuum cleaner is not a "hoover"

They look like a re-badged Megaflow to me! Same fittings, same immersion thermostat [damn expensive things they are!]

:|

 

[AAAMUSEMENTS]

They look like a re-badged Megaflow to me! Same fittings, same immersion thermostat [damn expensive things they are!] :|

Indeed they do. Are they perhaps a rebadged Plumbcentre own brand?

?:|

 

[paul b b]

the boiler is oil, the megaflows i think will run the showers.

no idea if the are relabled, i know they were half the price of a branded megaflow

 

[ProDave]

They look like a re-badged Megaflow to me! Same fittings, same immersion thermostat [damn expensive things they are!] :|

All different makes of pressurised water cylinders that I have seen have those same immersion heaters and thermostats. Dammed expensive things,