Gravity Heating System - Can I have on only the hot water

[Haggistrap]

Hello,

On a traditional Gravity system can you select to have only the hot water on and NOT the heating circuit?

I have an old (VERY! I have just moved house) heating system, its a traditional gravity fed heating system comprising;

Ideal Mexico Boiler (CF125)
Copper water cylinder
Heating circuit is pumped
Water is gravity, with cylinder stat and moterised valve to shut the water off when it reaches temp.
Potterton EP2000 programmer

The boiler has two heating circuits coming from it (4 pipes total), one for the central heating the other for the hot water.

All I want to be able to do is have the hot water on independanty from the heating. I have read various posts and Internet sites and I "think" this may be possible? I think the central heating can only be "on" if the boiler is on and therefore the hot water circuit too? But can the heating for the hot water be on and heating for the radiators be off?

My potterton EP2000 programmer will not allow the hot water and heating to be controled independantly. I was wondering if I could change to a different controller to allow the hot water to be turned on but not the central heating.

As of right now it appears there is no way to get hot water without running the whole system including the radiators. (no immersion heater)

I am considering conversion to fully pumped, but if I can simply alter the programmer to control independant hot water then I will stick there for a while.

Upgrading to a new boiler is going to cause major issues due to gas pipe size upgrades required......

Many thanks for reading and replys posted.

Terry

 

[doitall]

You can have hot water only but not heating only, without a major repipe etc.

Would be better upgrading the boiler if you go that road.

 

[Dan Robinson]

The heating side of the timer should just bring on the pump (ideally through a thermostat too).

You should already be able to have the hot water on WITHOUT heating.

Unless you convert to proper controls you will not be able to have heating on without the hot water.

You should be looking at a C-Plan or S-Plan layout.

 

[Haggistrap]

Two very quick responses, thanks!
So you both indicate it should be possible to have on the hot water only and NOT the heating?
It appears I need a new programmer?
I have looked here;
http://www.tlc-direct.co.uk/Technical/DataSheets/Horstmann/Horstmann_WiringGuide.pdf
and looked at the CentaurPlus C21 which is a direct replacement for my Potterton.
BUT, the instructions state when use with Gravity systems only single common on\off can be used for heating and hot water?

Can anyone advise on a suitable controller that will work with my boiler and allow the hot water to operate independently from the heating?

I am trying to avoid any pipe work changes i.e. C or Y plan. But that may ne the sensible way to proceed. But a new controller would be required anyway......

Thanks again,

 

[Dan Robinson]

C plan shouldn't require pipe changes, just the addition of a control valve and then the wiring required to control it.

Your current controller should be able to do what you want.
I suppose, it is a Potterton, and therefore will not be reliable

 

[Haggistrap]

Dan,

My Potterton Ep2000 will NOT allow the independent control of hot water and heating.

I have a reasonable understanding of my system. I think I have a C plan system in place, but no room stat installed.

Do I really need physical changes i.e. a control valve (not sure what \ where that would go!) to do what I want?

Or do I just need new controller with the ability to run the hot water circuit only?


This one appears to do what I want, can I just simply install it as a direct replacement?

http://www.timeguard.com/products/c...36-7-day-digital-heating-programmer-2-channel

Many thanks,

Terry

 

[Dan Robinson]

Unless you have a zone valve on the hot water primaries, you do not have a C-plan.

Your programmer SHOULD allow hot water only. If it doesn't then it is either installed wrong or faulty. You should have that checked before replacing it.

A C-Plan gives you the ability to have heating on without the hot water.

 

[Haggistrap]

Dan,

I think I have a "zone" valve (3 port moterised valve) on the feed from the boiler to the hot water cyliner. I think it's controlled via a cylinder temp stat. I assume this is to turn the hot water off when it reached the desired temp?

The Potterton EP 2xxx and 3xxx range appear to be designed to only allow hot water and heateing together. On my programmer it's physically not possible to have hot water on and heating off. The instaructions for the units appear to show this is correct i.e how they were designed??

Thanks,

Terry

 

[Dan Robinson]

a 3-port valve will not have gravity hot water.

I think you need to research your system a little more before deciding the course of action.

It seems you understand it less than you think.

 

[Haggistrap]

Dan,

As you can tell I am no expert and am picking up what I can along the way. Terminology is getting the better of me here.

There is an electronically controlled valve on the hot water circuit near the hot water cylinder. It controls the circuit dependent upon the temperature set by the cylinder thermostat. I am not sure if this is a Zone valve or a Port valve???

This is the only electronic valve I can see on the entire system.

Thanks,

Terry

 

[Haggistrap]

http://www.honeywelluk.com/Documents/All/pdf/936.pdf

This is the design of system I have but there is NO room stat and it's NOT got any honeywell components.

I am trying to understand if I can "simply" replace the Potterton EP 2000 controller with one that "allows" the hot water circuit to be on with the heating circuit off.

Thanks,

Terry

 

[JohnD]

You need a room stat. Spend your money there before you buy a new programmer.

some photos of your programmer, electric valve, cylinder stat and pipe layout will help us.

//www.diynot.com/forums/viewtopic.php?t=129539

 

[D_Hailsham]

There is an electronically controlled valve on the hot water circuit near the hot water cylinder. It controls the circuit dependent upon the temperature set by the cylinder thermostat. I am not sure if this is a Zone valve or a Port valve???

Which type of valve do you have - left pic or right?

View media item 5946 View media item 11762

 

[doitall]

Probably a tapstat DH

 

[Haggistrap]

It's the one on the right. (the two port version and it's a Honeywell)

And I need to correct my original information. I can turn the central heating off and just have the hot water on. The limitation of the programmer is that the on\off times refer be both the heating and hot water.

Photos

boiler, cylinder stat, valve, pump, programmer

//www.diynot.com/network/Haggistrap/albums/

My programmer can only do 24 hour cycles so would like a 5/2 or 7 day version.

Room stat would prob have to be a wireless unit.

Any recommendations on programmer \ room stat choices?

Simplistically does the room stat just kill the power to the pump on the heating circuit?

Thanks for all the feedback really appreciated!

Terry

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