central heating system questions

[jontwhale]

hi guys. complete amateur here!!!

my problem is this!
I have bought my first house (hoorah) but have some central heating and hot water probs.

First is that there are no cylinder stat or room stat which in the winter was chuffing expensive!!! there was an old prgrammer which i have replaced.
system is as follows.

Glowworm fuelsaver 2 boiler
horstmann c27 programmer
Honeywell valve 4043 22mm
Grundfos super selectric pump
Myson aerjec 22 de airator

i really dont even know what sort of system it is as reading on the web and what i have dont seem to add up.


The aerator thing seems to be sending water away from the pump according to the diagram on the front


The pump sends water through to the cylinder and also to the valve after the cylinder junction which appears to control the heating.


To valve is wired so that the brown wire is activated by ‘CH on’ on the programmer. The blue is wired into -. Earth is also wired in. the rest are not wired in on the valve, which points at a W plan, except it’s a 2 way motorized valve not a 3 way!!



The pump comes on when the hot water is called for. Which also confuses me as I thought it was a gravity HW system.

Everything I read on the web makes me think that this system is a bit messed up and leaves me stumped about wiring my thermostats in correctly.

What sort of system do you all reckon it is???

what would the best way be to put the stas in?

Jon

 

[Agile]

Well I give you full marks for good sharp pictures but its a pity that you have not shown what would have helped us more like a picture of the zone valve.

Wiring colours mean nothing because anyone can use any colour.

I would expect that you have a system which heats the hot water only on a pumped basis and if the valve opens then provides heating as well.

Thats quite good but runs the boiler all the time even when the water has got hot.

To add proper controls you will need to add a second two port valve and a cylinder stat.

In many ways it would be better for you to buy an ACL controls pack and start afresh with all new bits and wire it up yourself with the instructions.

Tony

 

[Gasguru]

Just beaten by Tony but here goes.


Your system setup is commonly found and is typical of a cheap lash up that basically works but has several shortfalls.

Currently there is no control of the stored hot water temperature other than by turning down the boiler thermostat (to prevent scalding water). The pump and boiler will run continuously during a programmed on time since there is no cylinder stat fitted.

The pump will run for both hot water and heating. The motorised valve opens for heating only. The original timeclock will have been setup in a such a way to prevent heating operation without the hot water on simulteaneously. This ensures the pump/boiler runs. The gate valve (technically should be a lockshield valve ie non adjustable by the user) balances the flow between the cylinder circuit and the radiator circuit.

Ignore the arrows on the aerjec - they point to the recommended setup, however from memory (and without checking the van library) there are alternative ways of connecting the device up.

The pump wiring box is underneath the pump - this is bad practice since leaks would constitute a hazard.

You need to check whether the boiler requires pump overun (some fuelsavers do) by looking at the boiler wiring connection. If it only has a L,N,E then it doesn't have pump overun.

In which case you could turn the system into S plan, ie add another zone valve for the hot water. Thermostats would be added for both hot water and room temperature. The timeclock may need reconfiguring to provide full control.

There may be sufficient room to fit the zone valve where the current gatevalve is. You will have a problem fitting in the lockshield valve. This would mean that while the hot water zone valve is open the radiator circuit will not have the required water flow and will cool down to some extent. Although not ideal it may be acceptable (and is commonly found).

Otherwise you are faced with significant pipework changes.

Check Honeywell site for S plan details but its the easiest setup.

 

[jontwhale]

thanks for the speedy replies, will put a proper respose in soon. got a stinker of a headache ATM ! thanks
do yo uthink i have a fully pumped system then?

 

[Gasguru]

Yes fully pumped.

 

[jontwhale]

excellent.

would it be a problem then if a second zone valve replaces the red stopcock (gatevalve?), as its after the cylinder?
would the pump get trashed if both valves were on stop at the same time? or would the pump be wired to come on with either the heating or the hot water?

Jon.

 

[Gasguru]

would it be a problem then if a second zone valve replaces the red stopcock (gatevalve?), as its after the cylinder?

As I mentioned before

There may be sufficient room to fit the zone valve where the current gatevalve is. You will have a problem fitting in the lockshield valve. This would mean that while the hot water zone valve is open the radiator circuit will not have the required water flow and will cool down to some extent. Although not ideal it may be acceptable (and is commonly found).

And regarding the pump

would the pump get trashed if both valves were on stop at the same time? or would the pump be wired to come on with either the heating or the hot water?

The pump will not run when the motorised valves are closed if the system is wired correctly. You must check to see if the boiler requires pump overun - see previous posting on this.

Details of S plan can be found here http://content.honeywell.com/uk/homes/systems.htm

if controls other than Honeywell are used the pin no.s may be different.

 

[Paul Barker]

with s plan don't fear the pump coming on with valves shut, because pump and boiler receive the phase (live) to make them work only after the valve has opened physically and a microswitch inside it has made contact.

In the case of pump overrun the phase from the zone valve is sent only to the boiler and the pump is controlled by the boiler circuitry via a permanent phase connection, in which case for s plan you would need an automatic bipass. For Y plan no need as it never shuts completely.

 

[ChrisR]

For Y plan no need as it never shuts completely.

(as long as there's a rad somewhere which is open, which means no trv, and two lockshields to stop it being shut)

 

[jontwhale]

the pump only has the 3 wires, live neutral and earth so guess there is no boiler over run.

i have a horstmann centaurplus c27 programmer so will follow the wiring diagram on here http://www.tlc-direct.co.uk/Technical/DataSheets/Horstmann/Pics.pdf

and get the second zone valve to make it all work properly!

out of interest where is the best place to get the zone valves online? ill be looking at getting the same model. Honeywell 4043 22mm.

Jon

 

[Paul Barker]

pumps will always have three wires, boilers on the other hand might have extra wires.

 

[Gasguru]

the pump only has the 3 wires, live neutral and earth so guess there is no boiler over run

No, no, no, no, no, no and no again, read my previous post

You need to check whether the boiler requires pump overun (some fuelsavers do) by looking at the boiler wiring connection. If it only has a L,N,E then it doesn't have pump overun.

Look at the boiler where the wiring connects, if there are only connections for L,N and E then it doesn't require pump overun. The pump itself will always have L,N and E otherwise it wouldn't run.

I ask this because some fuelsavers had pump overun ie the boiler controls the pump directly and you would need a different pipework configuration to the one we are proposing.

The diagram from TLC is a standard wiring schematic using Honeywell room and cylinder thermostats - if other makes are used the pins are likely to be different.

If you trust ebay they often have Honeywell zone valves.

 

[jontwhale]

lol. this is probably why i'm booked in for eye laser surgery tomoro!!!

the boiler has only 3 wires also! on the wiring picture its the grey wire on the right. with black, red and earth coming from it.

Jon

 

[jontwhale]

im gonna have to resurrect this one from the dead im afraid!
I FINALLY got this lot sorted out. room stat, tank stat, second valve in place of the stopcock.

Now i have a new problem!! the boiler goes out after the timer goes off. seems like there's a boiling sound from within the boiler (funnily enough!) then a loud click and it goes off. seems like a safety cut off.

the only thing that has changed within the water system is the new valve. i'm thinking that pressure is building up until the boiler switches off. its only when both valves are closed!

from the previous pictures the Aerjec seems to be plumbed in incorrectly.

Untitled

• jontwhale
• 22 Oct 2008
• 1

the water flows as per the picture, 1 or 2 is the cold water feed / vent and vice versa. looking on the aerjec website this setup is not one of the ones which work.

would the aerjec be the only expansion pipe on my system? is the problem likely to be what my puny brain thinks it is? how can i remedy it? at present i have my dhw valve manually open and the problem has gone!

HELP PLEASE!!

Cheers
jon

 

[bigbeak07]

just an airlock mate, turn both zone valves to manual then switch system on. leave running for a little while to clear air. after that switch system off close valves to auto setting then try again.