Help with Evohome / Opentherm / Intergas

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  • fergie
    Automated Home Sr Member
    • Mar 2017
    • 92

    #76
    Any reason why they are all working 'perfectly'?

    Comment

    • mtmcgavock
      Automated Home Legend
      • Mar 2017
      • 507

      #77
      Originally posted by The EVOHOME Shop View Post
      This is not entirely true.

      G3 regulations don't actually state you need a 2 port valve. What the regs say is that the heat demand to the coil needs to be removed when there is a high limit situation. This can actually be achieved by rotating a 3 port valve 180 degrees so the closed port is on the hot water side instead of heating. It is loosely called 'D-Plan' after Dan from Jennings Heating who came up with the idea (although others claim they were doing it earlier).

      I actually prefer hot water priority with a 'inverted' 3 port diverter valve - works much better with OpenTherm and evohome.

      As for OpenTherm, evohome and Intergas... I have all 3 things working just perfect in our training facility! ����
      Sorry I have to disagree with that, I think you'll find that every Unvented cylinder comes supplied with a 2 Port valve, along with clearly stating in the instructions that the valve must be fitted. As you state that regulations say that the heat demand needs to be removed, by fitting a 3 port or even diverter valve cannot guarantee this. Many 3 port valves pass on the HW side not providing a full shut off, along with the fact that in case of power loss to the 3 port valve it will fall to it's naturally open position which is HW. This then isn't closing the circuit, where as that a 2 port valve would close. Should power continue to a heat source (Such as the Boiler relay) it could prove quite deadly.

      The fact that you are advising people to do this is quite frankly worrying. If you want HW Priority just wire the system accordingly with the 2 Port valves.

      Comment

      • The EVOHOME Shop
        Site Sponsor
        • Dec 2014
        • 483

        #78
        Originally posted by mtmcgavock View Post
        Sorry I have to disagree with that, I think you'll find that every Unvented cylinder comes supplied with a 2 Port valve, along with clearly stating in the instructions that the valve must be fitted. As you state that regulations say that the heat demand needs to be removed, by fitting a 3 port or even diverter valve cannot guarantee this. Many 3 port valves pass on the HW side not providing a full shut off, along with the fact that in case of power loss to the 3 port valve it will fall to it's naturally open position which is HW. This then isn't closing the circuit, where as that a 2 port valve would close. Should power continue to a heat source (Such as the Boiler relay) it could prove quite deadly.

        The fact that you are advising people to do this is quite frankly worrying. If you want HW Priority just wire the system accordingly with the 2 Port valves.
        I'm sorry but this is showing a lack in your knowledge not mine.

        I have stated that the 3 port valve would have to be reversed 180 degrees so the 'open' port 'B' is on the heating side and therefore when the power is cut to the valve it closes the hot water port - absolutely no different to a 2 port. I have seen many cases where 2 port valves have failed open and the fact most 3 port valves are made with the very same mechanism as most 2 port valves (I have only ever fit Honeywell valves) makes what I have described no different. It is just an intelligent way of looking at the problem and finding an engineering solution.

        People like to make their own regulations up in the heating industry and there is nothing wrong with what I have suggested. As for unvented cylinders, unless you have completely bypassed the T&P valve by capping it off and also removed the high limit thermostat on the boiler, I can't really see how a 'deadly' situation would occur? More likely an immersion heater to cause issues with unvented cylinders than a gas boiler ever would.

        Comment

        • mtmcgavock
          Automated Home Legend
          • Mar 2017
          • 507

          #79
          Originally posted by The EVOHOME Shop View Post
          I'm sorry but this is showing a lack in your knowledge not mine.

          I have stated that the 3 port valve would have to be reversed 180 degrees so the 'open' port 'B' is on the heating side and therefore when the power is cut to the valve it closes the hot water port - absolutely no different to a 2 port. I have seen many cases where 2 port valves have failed open and the fact most 3 port valves are made with the very same mechanism as most 2 port valves (I have only ever fit Honeywell valves) makes what I have described no different. It is just an intelligent way of looking at the problem and finding an engineering solution.

          People like to make their own regulations up in the heating industry and there is nothing wrong with what I have suggested. As for unvented cylinders, unless you have completely bypassed the T&P valve by capping it off and also removed the high limit thermostat on the boiler, I can't really see how a 'deadly' situation would occur? More likely an immersion heater to cause issues with unvented cylinders than a gas boiler ever would.
          So when you've fitted the reserved 3 port, what happens when someone else, who isn't the original installer comes along when the valve has failed and says this hasn't been fitted correctly (Not aware of the situation). He then puts it on the right way round and leaves it - your are opening a can of worms.

          I've seen many situations where a 3 port valve has been fitted to a unvented cylinder where the high limit stat has cut out and heat still being transferred. On one particular occasion where a Worcester had been fitted with a pump over run and no bypass so it was pumping the heat round the cylinder. On this one it was discharging at a considerable rate, should that T&P failed it could have lead to a serious problem.

          Another occasion where a Viessmann boiler with internal diverter had been fitted, the temperature sensor had fallen out and the HW left on constant. Resulted in the cylinder overheating with no thermal cut off. Had a 2 port valve been fitted following the manufacturers instructions it would have prevented this.

          Whilst I agree it is very unlikely a deadly situation could occur as a number of components in the chain would have to fail, starting to deviate from the manufactures instructions shouldn't occur. The regulations are there, but the manufactures instructions should be followed. If you had an issue down the line they'd be very quick to say it wasn't fitted correctly. As gas safe always state with gas appliances, always follow the manufactures instructions.

          Use a 3 port valve, but put a 2 port valve before the cylinder. At least then should anything change on the installation that's out of your control you've always got the fail safe of the 2 port valve.

          Comment

          • DBMandrake
            Automated Home Legend
            • Sep 2014
            • 2361

            #80
            How exactly would an unvented cylinder overheat to the point of dangerous pressure release when heated by a closed loop to a boiler ? It can't get any hotter than the flow temperature of the boiler - which unless the boiler is faulty, is going to be under 90 degrees. (So now you have two separate devices failing at once to cause a problem, and that's pretty hard to protect against)

            From an electric element its possible, yes, because the electric element can reach several hundred degrees...

            Comment

            • mtmcgavock
              Automated Home Legend
              • Mar 2017
              • 507

              #81
              Originally posted by DBMandrake View Post
              How exactly would an unvented cylinder overheat to the point of dangerous pressure release when heated by a closed loop to a boiler ? It can't get any hotter than the flow temperature of the boiler - which unless the boiler is faulty, is going to be under 90 degrees. (So now you have two separate devices failing at once to cause a problem, and that's pretty hard to protect against)

              From an electric element its possible, yes, because the electric element can reach several hundred degrees...
              It wouldn't, unless like you state your boiler stat failed. I agree it's highly unlikely that you are going to get more than one safety device failing at once.

              The above particular situations, the Viessmann one hadn't discharged. The one with the 3 port valve I'm not quite sure what had happened in that situation regarding the discharge - but it had been discharging.

              Comment

              • The EVOHOME Shop
                Site Sponsor
                • Dec 2014
                • 483

                #82
                Originally posted by mtmcgavock View Post
                So when you've fitted the reserved 3 port, what happens when someone else, who isn't the original installer comes along when the valve has failed and says this hasn't been fitted correctly (Not aware of the situation). He then puts it on the right way round and leaves it - your are opening a can of worms.
                Customers are more intelligent than you give them credit for (or certainly that's my experience of being in the trade and dealing with 1000's of customers through our multiple businesses) - tell them this is what you have done and that they can contact the installer if they need any further information. I personally have always left plans of my heating system design with the customer and this removes possible conflicts in the future.

                Originally posted by mtmcgavock View Post
                I've seen many situations where a 3 port valve has been fitted to a unvented cylinder where the high limit stat has cut out and heat still being transferred. On one particular occasion where a Worcester had been fitted with a pump over run and no bypass so it was pumping the heat round the cylinder. On this one it was discharging at a considerable rate, should that T&P failed it could have lead to a serious problem.
                This is nonsense. A 3 port valve fitted 'correctly' as you say would pass water to the unvented cylinder without a 2 port valve... Things naturally fail that's why there are multiple safety systems that should be checked annually.

                Originally posted by mtmcgavock View Post
                Another occasion where a Viessmann boiler with internal diverter had been fitted, the temperature sensor had fallen out and the HW left on constant. Resulted in the cylinder overheating with no thermal cut off. Had a 2 port valve been fitted following the manufacturers instructions it would have prevented this.
                Above 88 degrees from the boiler? I would imagine it was hot but still not dangerous - you are making excuses now.

                Originally posted by mtmcgavock View Post
                Whilst I agree it is very unlikely a deadly situation could occur as a number of components in the chain would have to fail, starting to deviate from the manufactures instructions shouldn't occur. The regulations are there, but the manufactures instructions should be followed. If you had an issue down the line they'd be very quick to say it wasn't fitted correctly. As gas safe always state with gas appliances, always follow the manufactures instructions.
                Most manufacturers would be happy using a 3 port valve in the method I have described - I know Joule have no issues with this.

                Originally posted by mtmcgavock View Post
                Use a 3 port valve, but put a 2 port valve before the cylinder. At least then should anything change on the installation that's out of your control you've always got the fail safe of the 2 port valve.
                Why? This would be like fitting a 2 port valve and then fitting a second 2 port valve behind it (and seems ridiculous from an engineering perspective).

                Comment

                • mtmcgavock
                  Automated Home Legend
                  • Mar 2017
                  • 507

                  #83
                  Originally posted by The EVOHOME Shop View Post
                  Customers are more intelligent than you give them credit for (or certainly that's my experience of being in the trade and dealing with 1000's of customers through our multiple businesses) - tell them this is what you have done and that they can contact the installer if they need any further information. I personally have always left plans of my heating system design with the customer and this removes possible conflicts in the future.
                  This may well be the case, however how do you account for if the house is sold, plans lost etc.


                  Originally posted by The EVOHOME Shop View Post
                  This is nonsense. A 3 port valve fitted 'correctly' as you say would pass water to the unvented cylinder without a 2 port valve... Things naturally fail that's why there are multiple safety systems that should be checked annually.
                  Quite correct that should be checked annually. But people aren't educated enough regarding servicing and unfortunately this doesn't always get done. When someone buys a new build they tell them the boiler needs servicing but mention nothing of the unvented cylinder they have.

                  Originally posted by The EVOHOME Shop View Post
                  Above 88 degrees from the boiler? I would imagine it was hot but still not dangerous - you are making excuses now.
                  I can't remember the exact temperature, but it was over 80. To me hot water at over 80c, that's dangerous coming out of a tap that isn't a mixer or thermostatically mixed. Might not be dangerous in terms of the cylinder, but wouldn't have been so far off discharging (My Megaflo is set at 90oc).


                  Originally posted by The EVOHOME Shop View Post
                  Most manufacturers would be happy using a 3 port valve in the method I have described - I know Joule have no issues with this.
                  All the manufactures we fit I know clearly state in the book that the 2 port valve must be installed, even one manufacture goes on to say that if a Mid Postion is used then the 2 port must be installed afterwards. "This valve must also be used in a flow share (Y Plan) system, in conjunction with the mid-position valve, to act as a safety cut out valve."


                  I'd like to see Heatrae or one of the other big manufactures put it in writing that it's fine to do what you are saying. Also why would they send a 2 port valve with every cylinder if it wasn't necessary? They could save themselves a fortune.


                  Originally posted by The EVOHOME Shop View Post
                  Why? This would be like fitting a 2 port valve and then fitting a second 2 port valve behind it (and seems ridiculous from an engineering perspective).
                  I quite agree with you on the terms of it's a ridiculous idea, so why not just fit 2 valves? (CH & HW)

                  Whilst I quite respect where you are coming from, I think we'll have to agree to disagree on this one.

                  Comment

                  • HenGus
                    Automated Home Legend
                    • May 2014
                    • 1001

                    #84
                    Whilst customers may be intelligent, the same cannot be said for all installers. Recently, I had an issue with the Combination Valve on my Oso cylinder. I called out 2 G3 engineers to look at the problem. One failed to comment on the fact that the valve had been installed at the bottom of the cylinder - below the Tundish - and he couldn't tell me why the cylinder was failing to hold an air gap. The second engineer took one look at the valve and then went outside to check the outflow pipe which he could see was dripping water from it. He explained to me why it was important that the Combination Valve was positioned above the Tundish. Obvious when one thinks about it. The other engineer came back with a quote just to replace the old valve with no change to the pipework! Had I not asked for two quotes, I suspect that I would have been none the wiser.

                    FWiW, I had a new boiler installed earlier this year. The installer has left the original HW (2-port) valve in place wired as per OSO's installation manual. The CH 2-port valve was replaced with an inline valve to give HW priority (it closes when the HW valve opens).

                    Comment

                    • the crooner
                      Automated Home Jr Member
                      • Jun 2017
                      • 33

                      #85
                      Interesting.

                      The Megaflow we are having installed will have two motorised valves on the hot water feed, one controlled by the tank, set at the tank maximum, one controlled by the Evohome cylinder kit.

                      Overkill? Probabably, but since we paid for both valves we may as well use them.

                      As an interested, and very experienced amateur I am constantly amazed that you require a certificate to install a non-vented cylinder, yet there seems to be disagreement in the trade about how to do it. Makes me wonder if certification is just another way of persuading those of us who are totally competent, but lacking the certificate, to part with our cash.

                      Far better if we were able to carry out the work and have it signed of by building control.

                      Grenfell Tower reminds us all that experts are often that in name only, and that you should take even expert advice with a pinch of salt. Caveat emptor for services and goods.

                      Comment

                      • The EVOHOME Shop
                        Site Sponsor
                        • Dec 2014
                        • 483

                        #86
                        Originally posted by the crooner View Post
                        Interesting.

                        The Megaflow we are having installed will have two motorised valves on the hot water feed, one controlled by the tank, set at the tank maximum, one controlled by the Evohome cylinder kit.

                        Overkill? Probabably, but since we paid for both valves we may as well use them.

                        As an interested, and very experienced amateur I am constantly amazed that you require a certificate to install a non-vented cylinder, yet there seems to be disagreement in the trade about how to do it. Makes me wonder if certification is just another way of persuading those of us who are totally competent, but lacking the certificate, to part with our cash.

                        Far better if we were able to carry out the work and have it signed of by building control.

                        Grenfell Tower reminds us all that experts are often that in name only, and that you should take even expert advice with a pinch of salt. Caveat emptor for services and goods.
                        G3 is a legal requirement for fitting Unvented Cylinders for those that install them, but this doesn't stop people fitting them wrong.

                        However, as a second generation heating installer, do I think the G3 regulations are out of date? YES I do!

                        Unfortunately installers have stopped thinking about heating systems and just follow the 'rules' without question, as per the conversation above. Many installers don't even understand basic heating system design.

                        It is not the fault of installers that they have stopped thinking, as it is easier to just throw systems in as you are told to. However, this may mean that the best engineering solution for the customer is missed, especially with OpenTherm and energy saving minded people like me (an extra 22mm 2 port valve on a system is a waste of money and energy in my opinion). We are going into times where energy waste must be minimised.

                        I am currently working on the evohome and the Intergas modulation 'issue'. Some installers have stopped fitting evohome with Intergas boilers because of this issue. On initial assessment there seems to be a lack understanding from installers about evohome and OpenTherm. The good news is that I now have 3 evohome and Intergas ECO RF systems working and fully modulating on OpenTherm (and a robust way of getting it to work).

                        There will be more news to this to follow soon, but it's really good news for us as we specialise in the sale of both products online! 👍🏻

                        Comment

                        • bruce_miranda
                          Automated Home Legend
                          • Jul 2014
                          • 2307

                          #87
                          i still don't understand what the issue is/was with OT and Intergas. I never quite understood the "won't work with multiple zones" issue. i know that Viesmann and Ideal had the issue of the boiler ignoring its own set max and heating till it's physical max. But has anyone actually articulated the issue with the Intergas?

                          Comment

                          • The EVOHOME Shop
                            Site Sponsor
                            • Dec 2014
                            • 483

                            #88
                            Originally posted by bruce_miranda View Post
                            i still don't understand what the issue is/was with OT and Intergas. I never quite understood the "won't work with multiple zones" issue. i know that Viesmann and Ideal had the issue of the boiler ignoring its own set max and heating till it's physical max. But has anyone actually articulated the issue with the Intergas?
                            Intergas and Honeywell are well aware of the situation. At the end of the day it is in the interests of a manufacturers producing OpenTherm products to get this right, especially if UK law changes and modulating controls become a requirement.

                            Comment

                            • fergie
                              Automated Home Sr Member
                              • Mar 2017
                              • 92

                              #89
                              So what was at fault and how was it resolved?

                              I was going to install an Intergas ecoRF until they (installer talking directly to intergas) admitted it wouldn't work correctly with OT multizones.

                              Comment

                              • The EVOHOME Shop
                                Site Sponsor
                                • Dec 2014
                                • 483

                                #90
                                Originally posted by fergie View Post
                                So what was at fault and how was it resolved?
                                Right now I am going to say 'installer error' as not many people know evohome and Intergas like we do. I think there is a lack of understanding around OpenTherm, hence we have setup a training facility which will be dedicated to it here.

                                Comment

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