All radiators either on or off

[willdonal]

Are you saying that it reads the temperature correctly as 65 on the screen but doesn't seem to be controlling it properly ?

Check to make sure that your hot water BDR91 and hot water zone valves are working properly.

The green light on the hot water BDR91 should only come on when hot water is scheduled on and it is below the set point. Make sure this light is not coming on when there is only a heating demand. If this relay has been double bound it might be coming on when you have heating demand and thus the hot water temperature keeps rises towards the boilers flow temperature...

It could also be caused by a wiring error in the wiring centre or a problem with the hot water zone valve. Make sure the hot water zone valve is indeed closed when the hot water temperature is above your set temperature.

I'm also in agreement with others - don't set your hot water to 45 - that's too low to kill bacteria. 50-55 is the minimum safe temperature. I have mine set to 54. Hopefully you have blending taps so you can blend in a little cold water for comfortable and safe washing of hands.

Ive just put the heating on and checked the BDR91 and the water one is not on. Ive turned the hot water min temp under system parameters to 50 with a differential of 5 and a hot water overrun of 10 minutes. the temp at the moment is reading 57. it seems to fluctuate between 50 and 65. I will monitor over the next few days to see if it changes :-) :-) Thanks

[willdonal]

I would still think in terms of Occam’s Razor and rule out binding issues.

http://www.honeywelluk.com/professional-zone/resource-centre/product-videos/Clearing-a-binding-from-a-wireless-relay-box/Clearing-a-binding-from-a-wireless-relay-box

Set the HW over-run to one minute while you are at it.

Will Do, but what does the overrun do?

[willdonal]

Agreed, 10 minutes is too long. Try a hot water overrun of 1 minute or at most 2 minutes. I still don't think a long overrun could cause an overshoot of nearly 20 degrees though, as the boiler would be off during the overrun...

Sorry just noticed your message, I've changed the overrun to 1 minute. I will monitor over the next few days. Thanks

[willdonal]

Keep it at 60c. It does not have to be on long, but that of course depends on use. Mine is on for an hour in the morning and 30 minutes at night and I find it quite sufficient. There is always cold water to cool it down. Currently my app says the tank temperature is 35c. It will come on at 18:00 for 30 minutes but I know it will be up to 60c in a very short time.

Thanks, I have turned the temperature up :-) :-) I have it coming on for and hour in the morning and an hour at night. Perhaps this is a bit of an overkill if you say you only have it on for 30 minutes at night

[HenGus]

Thanks, I have turned the temperature up :-) :-) I have it coming on for and hour in the morning and an hour at night. Perhaps this is a bit of an overkill if you say you only have it on for 30 minutes at night

I think that the ON time demands on your needs and HW usage. My system is set up for HW priority. HW heating comes on at 6am (actually 5.57 as the Evohome clock is 3 minutes out). To get the cylinder up to 60C takes 40 to 45 minutes with my boiler flow TMax Set at 70C. The ON demand window closes at 8.30am which means that if either my wife or I have a bath/shower in the morning, the cylinder will re-heat to 60C.

Occasionally, I might have a shower in the evening and there is still more than enough hot water in the cylinder without re-heating it first.

[willdonal]

I think that the ON time demands on your needs and HW usage. My system is set up for HW priority. HW heating comes on at 6am (actually 5.57 as the Evohome clock is 3 minutes out). To get the cylinder up to 60C takes 40 to 45 minutes with my boiler flow TMax Set at 70C. The ON demand window closes at 8.30am which means that if either my wife or I have a bath/shower in the morning, the cylinder will re-heat to 60C.

Occasionally, I might have a shower in the evening and there is still more than enough hot water in the cylinder without re-heating it first.

Thanks Hengus, I will have a play with the settings to see what best suits :-) :-)

[willdonal]

Good morning everyone, After the trial and tribulations the heating is working as advertised and I even have it programmed in to alexa so by saying 'alexa turn living room up to 25' Alexa then turns the temperature up. Brilliant this modern technology. However I still have one problem and that is the hot water. It has gone from been hot to taking the skin off your hands hot. This morning the evohome controller was reading 77 even though I have the water set to 50 on the controller. As someone has said earlier it could be that the water is been heated when the heating comes on. I have checked and the relay box green light for the water does not come on when the heating is on. Only the green light for the heating relay box comes on. I need help before I give myself third degree burns. If someone does suggest a reset and rebind then can you tell me exactly how to do the full reset on the wireless relay box and the hot water box/thermostat. thank-you :-) :-) :-)

[HenGus]

There is a possibility that your HW BDR hasn’t been wired in correctly. The cylinder temperature should never get above the temperature set on the cylinder thermostat irrespective of what Evohome is demanding. I posted a link to the Honeywell video on clearing the binding on a BDR. It involves a 15 sec button press on the BDR.

See the advice here:

https://theevohomeshop.co.uk/content/11-evo-help

Have you checked that the zone valve isn’t stuck in the open position?

[willdonal]

There is a possibility that your HW BDR hasn’t been wired in correctly. The cylinder temperature should never get above the temperature set on the cylinder thermostat irrespective of what Evohome is demanding. I posted a link to the Honeywell video on clearing the binding on a BDR. It involves a 15 sec button press on the BDR.

See the advice here:

https://theevohomeshop.co.uk/content/11-evo-help

Have you checked that the zone valve isn’t stuck in the open position?

Hello Hengus, reading the above link it states that the wireless relay boxes must be at least 300mm apart. as can be seen from the picture they are right next to each other. Could this have caused the problem? When the installer fitted everything he made all 3 valves to be permanently open, 1 valve controlled downstairs heating, 1 was for upstairs and the 3rd was for the hot water. Could be the problem? The picture shows the 2 boxes plus the blanking plate to where the heating control box was. ThanksIMG_0480.jpg

[DBMandrake]

Hello Hengus, reading the above link it states that the wireless relay boxes must be at least 300mm apart. as can be seen from the picture they are right next to each other. Could this have caused the problem? When the installer fitted everything he made all 3 valves to be permanently open, 1 valve controlled downstairs heating, 1 was for upstairs and the 3rd was for the hot water. Could be the problem? The picture shows the 2 boxes plus the blanking plate to where the heating control box was. Thanks[ATTACH=CONFIG]1090[/ATTACH]

Yes, the relays should be 300mm apart so they don't interfere with each other causing unreliable wireless comms and this should be sorted out, however this is probably not your specific issue.

If the Hot water zone valve has been wired to be permanently open then you have found your problem - of course the hot water will get too hot as soon as the boiler is running. Kind of hard to believe that the installer would make that sort of schoolboy error ?

If so, what is the hot water BDR91 wired to ? Nothing ? The hot water zone valve needs to be under the control of the hot water BDR91 or the system will have no control over hot water temperature at all. It's also worrying that you don't seem to have a safety thermostat for the cylinder (usually wired in series) functioning either - if you did it wouldn't get as high as 77 - that is hot enough to cause burns and is of grave concern especially if you have children in the house. This seems to be bordering on negligence and incompetence on the part of the installer if this is true.

[Dan_Robinson]

That picture is a disaster waiting to happen.

I predict that it will end up in a PowerPoint presentation in bracknell soon

[willdonal]

Yes, the relays should be 300mm apart so they don't interfere with each other causing unreliable wireless comms and this should be sorted out, however this is probably not your specific issue.

If the Hot water zone valve has been wired to be permanently open then you have found your problem - of course the hot water will get too hot as soon as the boiler is running. Kind of hard to believe that the installer would make that sort of schoolboy error ?

If so, what is the hot water BDR91 wired to ? Nothing ? The hot water zone valve needs to be under the control of the hot water BDR91 or the system will have no control over hot water temperature at all. It's also worrying that you don't seem to have a safety thermostat for the cylinder (usually wired in series) functioning either - if you did it wouldn't get as high as 77 - that is hot enough to cause burns and is of grave concern especially if you have children in the house. This seems to be bordering on negligence and incompetence on the part of the installer if this is true.

The BDR91 is connected to the thermostat that came with the hot water pack and is connected to the tank. That would explain why the temperature was 77 this morning when I had the heating on, now the heating is off the temperature has dropped to 60. As I had 3 zones would it be ok just to wire up the water valve and leave the two heating valves open? Unfortunately the installer had never installed one of these systems before but he did contact Honeywell for advice and so I assumed he had done it properly. we live and learn :-) :-)

[willdonal]

That picture is a disaster waiting to happen.

I predict that it will end up in a PowerPoint presentation in bracknell soon

Hi Dan, Didn't think it looked too good. I have now contacted an official Honeywell installer who is going to come next week and sort it all out. It is way beyond what I can do myself.
thanks for you expertise and help :-) :-)

[DBMandrake]

The BDR91 is connected to the thermostat that came with the hot water pack and is connected to the tank.

Normally you would have a safety thermostat built into the cylinder if it is an unvented cylinder, (regs demand it I think) set to cut out at around 65 degrees or so. This would get wired in series with the BDR91 and then go to the hot water zone valve. That way both the Evohome and the safety thermostat can cut the power to the hot water zone valve if the temperature is getting high.

That would explain why the temperature was 77 this morning when I had the heating on, now the heating is off the temperature has dropped to 60.

Yes - whenever the heating was on the hot water temperature would gradually climb towards the flow temperature of the boiler - it sounds like your boilers flow temperature is set very high too for this time of year, perhaps unnecessarily high. I have an old non-condensing system with old radiators that are designed for high flow temps and I still have mine set to only 65 at this time of the year although by the end of October I'll probably have to bump it up to 70.

As I had 3 zones would it be ok just to wire up the water valve and leave the two heating valves open?

Yes that's absolutely fine - generally with Evohome you would have HR92 radiator controllers on all radiators perhaps aside from a towel rail or bypass radiator so the heating zone valves for upstairs and downstairs become redundant because every room is its own zone - in that case you either mechanically latch them open, or my preferred option is to wire them to run off the pump's power supply - that way they always open when the pump runs but they also close when the heating is off to save power and make sure they don't seize from sitting open permanently.

Another option would be to wire both heating zone valves together to run off your heating BDR91 which would make it a standard S-Plan configuration. The advantage of this is that if you have any radiators without an HR92 like a towel rail, they would not get hot when only hot water is turned on - if the heating zone valves are always open when the system is on you will get some heat to towel rails in summer when only hot water is enabled.

Some people like that idea, some don't. I have HR92's on all my radiators and also (somewhat redundantly) a heating zone valve as well, so I don't get any radiators heating at all if I only have hot water enabled.

The hot water zone valve of course does need to be wired to both the hot water BDR91 and the cylinder safety stat if it has one. (If its unvented it will definitely have one, vented may not)

Unfortunately the installer had never installed one of these systems before but he did contact Honeywell for advice and so I assumed he had done it properly. we live and learn :-) :-)

Still not excusable on their part really - what you have or had sounds like a standard S-Plan+ system with a hot water zone valve and one or more heating zone valves.

In such a system the hot water zone valve is always what regulates the hot water temperature - previously it was probably controlled with a cylinder stat and a timer, now it is controlled by the hot water BDR91. (And a temperature reading from the Evohome cylinder sensor is sent back to the Evohome controller wirelessly so it knows when to switch that relay on and off)

Leaving the hot water zone valve wired or held open wouldn't be something you'd ever do on an S-Plan system.

[HenGus]

Hi Dan, Didn't think it looked too good. I have now contacted an official Honeywell installer who is going to come next week and sort it all out. It is way beyond what I can do myself.
thanks for you expertise and help :-) :-)

Wow. Clearly, the guy who made the wiring changes hadn't a clue about how the Evohome Hot Water Kit works. Have a long slow read of the installation manual as using a Honeywell Connected Installer is no guarantee - in my experience - that the guy knows what he is doing. It will depend on whether Evohome plays a part in his business. Unless things have changed, many installers only complete online training (which is available to the public). Even I managed to get a pass!