Heating and hot water controls - Hot water priority for HW + RADS?

[unclebob1]

Hi all,

I'm looking to rewire my control centre (the installer left it in a mess with wires hanging around everywhere) and figure out why my hot water is not coming on with the programmer.

Setup at the moment is:
Intergas boiler HRE

1 zone valve for hot water tank - 6 wire.
1 zone valve for radiators on 1st floor
1 zone valve UFH manifold - ground floor.


Wiring wise is setup for Hot water priority - the return from Hot water zone valve feeds the circut for the radiators zone valve.

UFH manifold does its own thing, so if hot water is on, and the UFH comes on, it will get the heat.

On the other hand, the UFH only needs low temperature water circulating. The Hot water and upstairs rads require a higher temperature...


What im thinking is can i setup the wiring such that the Hot water + rads are both connected as "DHW" on the boiler - set the temp to 65-70 degrees.

The UFH is then wired as central heating to the boiler, temp set to 40-45 degrees with a blender already on the manifold to any adjustments should the hot water or upstairs rads be on...

What are peoples thoughts on this?

At present hot water is not coming on at all, if i manually open the zone valve, the boiler kicks in for hot water mode and all works, so i suspect an issue with the programmer... 1st floor heating doesn't work unless i cycle through the hotwater settings on the programmer to turn On and then off the hot water! Its a "feature" of horstman programmers, but seem to be the only ones i can find which allow the return from the DHW zone valve to feed as the common for the heating program... most others seem to have a common live...

 

[CBW]

Do you have a photo/diagram of current wiring layout? What zone valves do you have?

 

[unclebob1]

Do you have a photo/diagram of current wiring layout? What zone valves do you have?

Im going to go though the wiring over xmas break, but as a rough guide i think it is:

Zone hot water (valve a) Danfoss hpa2C
zone for rad (valve b) -Danfoss hpa2
Zone for UFH (valve C) Danfoss hpa2

Programmer has E, L, N, HW-NC, HW-C, HW-O, CH-NC, CH-C, CH-O.

Loop from L to HWC.
Wire from HW-O goes to Themostat on HW tank, return from themostat demand goes to Orange on A. Thermosat no demand goes to wiring centre, and i think goes to CH-C along with White from Zone valve A and NW-NC also goes to CH-C.
CH-O goes to orange on Valve B.



(A)Orange is connected to live in control center, (A)grey is return when on going direct to the boiler i suspect to the hw contact, (A)white returns and feeds the programmer for central heating, which returns to feed (B)orange of the radiator zone valve (say valve b).

The grey from the radiator valve (valve b) returns to boiler as central heating contact, the UFH zone valve (valve c) grey also connects to the radiator return valve. (C) orange i think is connected to perm live...

Wiring colours on wiring centres is a mess so difficult to check and follow properly without taking the whole lot apart. Will try and get a wiring diagram together over the next few evenings.

 

[CBW]

Some of that doesn’t sound correct, also you mentioned a 6 wire zone valve, do you have a 3 port valve and or an unvented cylinder?

 

[unclebob1]

The description is from memory from what i could check in a limited way, but will check and get a diagram of sort drawn up (btw any recommendations for any software i can use outside of paintbrush?) It is a 6 wire zone valve - two port specifically changed from a 5 wire one for the hot water priority. its the hpa2C head on a hpa2 body.

EDIT - looking at other online diagrams etc, the grey and orange above may be reversed! in that grey is connected to programmer, orange output to the boiler..

 

[unclebob1]

Just found my own thread that i created last year, from which i gave the details to the installer... think they have loosely followed the attached diagram, but used 6 wire actuator instead of the relay...

Ive noticed the 9-10 needs to be OC so my initial idea wont work directly... will have a think again how to do this.

 

[CBW]

The description is from memory from what i could check in a limited way, but will check and get a diagram of sort drawn up (btw any recommendations for any software i can use outside of paintbrush?) It is a 6 wire zone valve - two port specifically changed from a 5 wire one for the hot water priority. its the hpa2C head on a hpa2 body.

EDIT - looking at other online diagrams etc, the grey and orange above may be reversed! in that grey is connected to programmer, orange output to the boiler..

Yes Grey is usually permanent live supply with Orange being the switched out

 

[unclebob1]

That said, looking at the diagram above, i guess there is no reason why the relay cant be energised from two different sources connecting to pin 14 on the base? Or would the orange from valve a backfeed up the orange for valve b and cause problems?

I dont really need to worry about the satisfied side on hot water thermostat and programmer. as I'm happy to have the UFH on, while the Hotwater/radiators are on, as the blending valve will reduce temp anyway?

If thats the case i can also ditch the current programmer?

 

[CBW]

I may a bit lost now, wiring and relays are not my forte

 

[unclebob1]

lol not to worry- looking at that diagram, i think i have got the plan in my head... will test it out on a spare actuator i have and see if it works...

Meanwhile - back to the original question, any reason why i can not do both HW and Rads running on contacts 9 and 10 (though flipped in terms of open contact for heat, and closed to stop) and UFH on the normal connections 6 and 7?

 

[CBW]

I think I get what you’re asking, so you want to control heating and hot water on one zone valve from the programmer? If so can’t see it working as the zone valves work from room and cylinder thermostats, if just wired in on cylinder thermostat you would be satisfying the cylinder and then heating would go off.

 

[oldbutnotdead]

Good grief, that looks complex. The hot water priority bit- that only really comes into play if there's a 3 port valve somewhere. If you only have 2 port zone valves then the simple (but less aesthetically pleasing) solution is 3 timers (I'd leave the DHW timer in a cupboard somewhere and use the fancy Hive/whatever nonsense for ground floor and 1st floor), 3 thermostats (DHW, downstairs, upstairs) and off you go.
A more cunning variant (since you're obviously comfortable with relays and logic diagrams) would be an on-delay relay triggered by your bathroom light switch- if the light is on for more than 5 minutes then override the DHW timeclock, if the cylinder stat has dropped to call then fire the boiler to top up the cylinder.
But maybe I'm missing something more subtle going on....

 

[muggles]

Be very very careful here. Terminals 9 & 10 are extra low voltage - 24 volts maximum. Try to put 230v through there and you'll be needing a new circuit board. That's what the relay is for. They're actually a connector for a cylinder thermistor, but can be used in an on/off fashion provided some kind of relay is used to separate mains voltage from the 9 & 10 terminals.

You can't flip the function of 9 & 10, because of their original use they work only as described. You shouldn't try to run CH off that side either - it'll tell the boiler to go to maximum rate and will make your CH inefficient. CH demands need to go via 6 & 7 as per the drawing.

Obviously can't see your setup here, but from your description it sounds like you might have a pipework fault as much as a wiring fault. Which bit of London are you in (assuming your profile is correct and you are in London!).

 

[unclebob1]

Apologies - only just saw the responses on this.

@oldbutnotdead - The timer for the dhw doesnt work without flipping the function.

@muggles - Yes i have a plumbing problem - at the moment my Rads and UFH seem to go though the hot water tank - so regardless of what is on, my hot water is heating up, beyond what the tank thermostat is set to.

In terms of inefficenty - My plan is to have DHW and upstairs rads at say 65 Degrees, while UFH can then run at say 40 degrees, the UFH is generally on for much longer so i'd rather the temprature of that be lower, so the mixing valve doesnt need to mix so much...
With regards to the 24v, at present the circuit for DHW is not powered by anything other then whatever is sent from 9 and 10. Ie no additional power is put in from the programmer.