Help with Multi Zone Required

[davidwicks100]

I have a complex heating system (At least it seems like it to me) It consists of


Heating Zones:

Zone 1 - Radiators
Zone 2 - Hot Water Tank 1
Zone 3 - Underfloor heating
Zone 4 - Hot Water tank 2
Zone 5 - Air Heating in swimming pool
Zone 6 - Water heating in Swimming Pool

Each zone has its own pump (6 pumps in total) and each has its own electric gate valve (6 in total)

Zone 1&2 are controlled from a standard central heating timer with tank and wall thermostat
Zone 3&4 are controlled from a standard central heating timer with tank and wall thermostat
Zone 5 has no timer because it is constantly on but does have a wall thermostat
Zone 6 has a timer and thermostat in the pool water heat exchanger

All of the zones are fed from a manifold type arrangement near the boiler and are either 28mm loop or 22mm loop. The pumps and the electric valves are located all over the place.


The Boiler:

There are 2 heat sources-

2 x electric boilers connected in parallel
1 x oil boiler connected in series to the electric boilers, but after the electric boilers in the flow.


The Problem:

The boilers are not connected in any way to the heat demand side of the system. they are powered constantly and use their own internal temperature to turn off. There is no overrun from a pump in order to empty the hot water from the boilers. The electric boilers are overheating and burning out the heating elements. I have just replaced them a couple of times, but they are getting a bit expensive to just keep doing that. I am also about to extend the property which will result in a further hot tank and some additional radiators.

What I Would like to achieve:

I would like to be able to link the whole system up in a more simple arrangement. Would like to have a single pump if possible, would like to have a single controller to time manage the hot water, radiators and under floor. I am not so worried about the pool heating being in a different place because it is not changed in the same way as the house is.

I could really do with some help on:

How can I get the system working in a more integrated way regarding boilers and heat demand. There will potentially be 7 zones once the extension is complete.

Can I get this all running from a single pump that can be integrated in a way that will remove excess heat from the electric boilers specifically, but I guess also the oil boiler.

What is available that can control the on/off heating of 3 water tanks, 1 radiator loop and 1 underfloor loop.

 

[electronicsuk]

You must have some pretty large boilers for the system to be capable of running all those heating and HW zones PLUS the water in a swimming pool.

I can't advise you on your odd arrangement of having the two electric boilers and parallel and then continuing on to the oil boiler, although if the oil boiler is condensing, this arrangement must surely be inefficient. Not to mention the huge cost of electrically heating a pool!

As for the electrical side of things, as you say each zone has it's own motorised valve, you will hopefully find that each of these valves is connected with a 5 core flex, two of those cores being for an internal microswitch which makes when the valve is open. These would normally be used to call for heat from the boiler, although I have a suspicion that the installer may have instead used them as a method of controlling the pump for each zone. Can you check this?

Pump overrun is going to be a little difficult, as it sounds as if the boilers themselves do not have a pump, and instead, each zone has it's own pump installed AFTER the motorised valve? If that's the case, you're always going to have a problem getting rid of any latent heat once those valves have all closed. If you can fit another pump directly onto the boiler connections before the manifold and wire it back to the boiler in order for it to have overrun capability, you could then fit a bypass valve to the pool heater circuit, which would be a rather large heat dump. This would of course also require each zone to be wired back to the boiler's call for heat connections.

Of course, I'm an electrician by trade and not a plumber, so you'd be best to wait for one of the RGIs to come along and have a gander. The whole setup sounds rather odd to me...

 

[D_Hailsham]

The experts on here will only be making educated guesses, considering how complex your system is.

It would be better if you paid a firm of consulting heating engineers for their advice. I'm sure you could afford it, if you can afford to heat a swimming pool.

 

[Biggles..]

your system sounds to be exactly as it should be designed.

Boilers on one side of a header,constantly firing but should be controlled either by their own thermostat or by a return pipe stat.

Load side of header is also quite normal. Motrised vales have bee used but you can do it without by controlling the pumps operation.

You'd be better off getting a controls engineer to look at it rather than re piping as its laid out at its most efficient now.

Immersions are burning out due to either stats being to high or having to constantly run to satisfy the pool, probably being undersized as the oil should be doing most of the heating.

Pool should have either 4 way valve or 3 port compensator for better use and to stop the constant demand for heat from the header.

All the heat that comes out from the header has to be put in so you boilers are probably struggling to satisfy your loading.