Evohome Hot Water Safety

[thepook]

Hi all,

I'm new here, so please go easy on me!

Its a fairly long one, so please bear with me...

I've got a fairly simple Evohome system, comprising a Base Pack, Hot Water Kit, Remote Gateway and 4 Radiator Valve Zones. It is connected to a Y-plan system, and my hot water cylinder is a vented type. The boiler is hard wired to the mid-position valve in the wiring centre.

I have installed it and cleared all binding on the BDR91s and factory reset the Controller. After that, I have set the 2 BDR91s as hot water and heating zone valves only - there is no boiler relay configured. Everything seems to be working perfectly from that point of view, the boiler interlocks work correctly and I can have heating only, dhw only and heating/dhw combined.

I understand that my configuration means that in the Installation/Parameter Settings menu, I don't get the Cycle Rate and Minimum On Time options, because I don't have a Boiler Relay configured. I was surprised to find that I also don't have the Fail Safe options to configure - is that correct? Do those options only apply to a Boiler Relay?

I am a little concerned about how safe the Hot Water control is via wireless only. In fact, last night I set the hot water on, so that the dhw relay called the dhw valve and fired the boiler, then took the batteries out of the hot water sensor by my cylinder for 30 minutes o test the safety features (was as long as I dared!). I was alarmed to find that the dhw relay carried-on calling for heat the whole time, before I bottled-out and put the batteries back in.

My question is, would the dhw relay have switched off at some point when the Evohome Controller finally decided that it had lost communication with the hot water temperature sensor, or would the water have continued to heat the dhw to a dangerous level? Does this relate to a missing Fail Safe menu on my Controller?

I am also considering refitting the old thermostat to the dhw cylinder, setting the temperature on it high and connecting the dhw call contacts in series with the output to the boiler from my wiring centre. That way, the Evohome would be controlling the dhw, but the old stat would act as an overheat stat and prevent the boiler firing at all. I know a back-up thermostat is not strictly required on a vented cylinder, but I'd like it as safe as possible.

Thank you in advance for your help.

Thepook

[SensibleHeatUK]

We never remove the cylinder thermostat on our installs, even with unvented cylinders, as it can be used as a limit stat as you suggest. However even if these devices fail you are still only going to raise the stored hot water to a maximum of boiler temperature, so to some extent it is self-limiting in a failure be ause of this albeit it at a high temperature.

[thepook]

Thanks for the reply - how do you normally use the old thermostat with a y-plan, or do you convert to an s-plan?

Do you know why my Evohome controller would not have the Fail Safe menu items? Is it because I don't have a boiler relay configured?

I've also noticed that I don't have the Error Logbook menu item under settings - does that only appear if there is an error recorded?

Thanks again

[HenGus]

I've also noticed that I don't have the Error Logbook menu item under settings - does that only appear if there is an error recorded?

Yes. It clears after a controller re-set.

[thepook]

Thanks for the confirmation .

[HenGus]

Thanks for the confirmation .

No problem. I only know because my controller re-set and the 4 pages of faults disappeared. I now have 2 pages of Comms faults after some Comms issues earlier this week. This forum is a great source of information from those who know a lot about the system and, occasionally, from those of us who don't" I have also found Evohome Support to be extremely helpful.

[thepook]

Thanks - who do you contact at Evohome Support - it seems to me that they only want to offer support to their installers, even though you can buy the product in retail outlets!

[HenGus]

Thanks - who do you contact at Evohome Support - it seems to me that they only want to offer support to their installers, even though you can buy the product in retail outlets!

I usually ring 0300 130 1299 or e-mail them. The details are on their website:


Customer services operates during business hours, Monday – Friday , 9am – 5pm and can alternatively be reached via telephone. Please refer to the contact section of http://evohome.honeywell.com for your local number.

To find out all the latest news and info or trying to find an installer who can advise on evohome, please visit http://evohome.honeywell.com

To find out more about the Total Connect Comfort App and where to download, please visit https://infoeu.mytotalconnectcomfort.com/

Or alternatively follow us on Twitter @HON_Home_EU for tips and tricks and the latest news.

The evohome Team

[The EVOHOME Shop]

Thanks - who do you contact at Evohome Support - it seems to me that they only want to offer support to their installers, even though you can buy the product in retail outlets!

People who buy from us have my full technical support and experience on speed dial...

[top brake]

Hot water is indeed an area that you need to be a competent person to work on, and if you aren't confident it is best left to the professional. It's like when I see questions on car forums about how to change brake pads.

[HenGus]

Hot water is indeed an area that you need to be a competent person to work on, and if you aren't confident it is best left to the professional. It's like when I see questions on car forums about how to change brake pads.

I am intrigued by the use of the words 'competent person'. Having recently had a plumber back three times to make good the leak on a toilet bowl installation that he carried out, and my Evohome Specialist Installer returning on Monday for the third time to move the BDRs, I am not sure that the man in street has the ability to determine who is competent and who is not. That said, I have a very good heating engineer who looks after my boiler - but refuses to touch Evohome - and the most amazing electrician that I have ever seen seen install my PV Solar. The heating engineer came via my boiler maintenance/insurance scheme and the electrician just happened to be part of the PV Solar company's installation team. He travelled over a 100 miles to do the work.

[top brake]

I am intrigued by the use of the words 'competent person'. Having recently had a plumber back three times to make good the leak on a toilet bowl installation that he carried out, and my Evohome Specialist Installer returning on Monday for the third time to move the BDRs, I am not sure that the man in street has the ability to determine who is competent and who is not. That said, I have a very good heating engineer who looks after my boiler - but refuses to touch Evohome - and the most amazing electrician that I have ever seen seen install my PV Solar. The heating engineer came via my boiler maintenance/insurance scheme and the electrician just happened to be part of the PV Solar company's installation team. He travelled over a 100 miles to do the work.

http://www.hse.gov.uk/involvement/competentperson.htm

[thepook]

http://www.hse.gov.uk/involvement/competentperson.htm

Yes, think I understand the sentiment of the post Re: safety, but I would hope that you understand my view of safety, given that I am asking questions about the fail safe behaviour of the system that are not answered by the manuals, the manufacturer's own online training, or as yet their own customer services department. I have also added a secondary thermostat to my system that is hard wired for safety, even though not specifically required for vented systems.

I would also add that my experiences so far in life tell me that there is a vast gulf between being trained and being truly competent.

[top brake]

Yes, think I understand the sentiment of the post Re: safety, but I would hope that you understand my view of safety, given that I am asking questions about the fail safe behaviour of the system that are not answered by the manuals, the manufacturer's own online training, or as yet their own customer services department. I have also added a secondary thermostat to my system that is hard wired for safety, even though not specifically required for vented systems.

I would also add that my experiences so far in life tell me that there is a vast gulf between being trained and being truly competent.

Have a read of the building regulations part G3, it's all there

As far as your system with a vented cylinder it cannot get hotter than the output of your boiler and as it is vented cannot pressurise
If you are worried about scalding you should consider to fit TMV to your taps

Getting back to the evo system fail safe refers to keeping the space heating going if there is a loss of communication

Hope this answers some of your questions, if not please ask away

[thepook]

Have a read of the building regulations part G3, it's all there

As far as your system with a vented cylinder it cannot get hotter than the output of your boiler and as it is vented cannot pressurise
If you are worried about scalding you should consider to fit TMV to your taps

Getting back to the evo system fail safe refers to keeping the space heating going if there is a loss of communication

Hope this answers some of your questions, if not please ask away

Have already read and understood G3, and my system complies completely for a replacement of existing.

My controller does not offer the fail safe settings option - it seems that these only appear if you have a boiler demand relay configured. My question to Honeywell was what fail safe behaviour applies when you only have 2 BDR91s acting as heating and dhw zone valves.

I agree entirely about the max possible temps, but my boiler can output 86 deg, so I have set the Evohome to 60 deg and have the secondary stat set just over 65, so it normally does nothing, but in a fault limits the dhw temp - seems a lot safer than depending on wireless to me, plus its no real trouble on an existing system with a stat. It should really be the recommended standard installation for wireless systems imho.

I also understand and agree about the TMV comment.