Atag IS24 Plus Evohome Plus Opentherm

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  • fergie
    Automated Home Sr Member
    • Mar 2017
    • 92

    #46
    I'm about 16 rads + unvented cylinder. I'm currently running evohome with 12 valves and not connected to the current glowworm boiler at all. I'm hoping to go OT once I get a new boiler sorted.

    I'll drop you a pm.

    Comment

    • Sean in Amersham
      Automated Home Jr Member
      • Jan 2017
      • 15

      #47
      HenGus,

      I have been watching your progress with the Atag with interest after my own wrong boiler choice last year (Worcester Bosch 24RI - noise and vibration issues causing no sleep in nearby bedroom).
      I may replace the WB with a OT type boiler now.
      If you had your time again would you advise on going for the Atag again?
      Is there an installer you would recommend? (I am as my moniker suggests in Amersham, Bucks).
      I run Evohome with UFH (ground floor), Rads (1st and 2nd floors) and two Megaflo tanks in a larger recent build 5 bed property with high insulation and all with differing heat timing requirements, so mostly no multiple heat loads being called for at the same time.

      Comment

      • HenGus
        Automated Home Legend
        • May 2014
        • 1001

        #48
        Originally posted by Sean in Amersham View Post
        HenGus,

        I have been watching your progress with the Atag with interest after my own wrong boiler choice last year (Worcester Bosch 24RI - noise and vibration issues causing no sleep in nearby bedroom).
        I may replace the WB with a OT type boiler now.
        If you had your time again would you advise on going for the Atag again?
        Is there an installer you would recommend? (I am as my moniker suggests in Amersham, Bucks).
        I run Evohome with UFH (ground floor), Rads (1st and 2nd floors) and two Megaflo tanks in a larger recent build 5 bed property with high insulation and all with differing heat timing requirements, so mostly no multiple heat loads being called for at the same time.
        That's a difficult one to answer as the new boiler has been installed for less than a month. That said, I have no regrets so far. The boiler is whisper quiet in operation and the set up with my existing Evohome system was nothing more complicated than deleting the existing heating BDR from the Controller (unbinding the BDR just to be doubly sure) and then setting up the OT bridge as a boiler relay.

        I used an Atag recommended installer and the boiler warranty has been increased to 10 years at no additional cost to me. My installer insisted on a full water flush which, with 19 radiators, took most of a day. Throughout the flushing process, he took repeated water PH, Fe and ionisation samples and the system has been installed to comply with the latest German Standards on CH systems without any inhibitor. The system is protected from rusting etc with a SpiroVent Microbubble De-aerator and SpiroTrap Dirt Separator. The logic behind this is that clean water without the presence of air cannot cause rust, whereas a system with too much/too little inhibitor can. Interestingly, on the afternoon of the flush, I had three other CH installers visit all armed with their brand new ( and very expensive ) water testing kits getting some hands-on onsite training from my installer.

        Why Atag? Firstly, in the Netherlands, Opentherm for new systems is the norm. That said, I was aware from this forum that others were using Valliant, Ideal and Viessmann with Opentherm. Various posts on this forum, and others, pointed out some of the issues. I won't repeat them all here. I found myself leaning towards the Intergas RF Eco. It is listed as fully compatible with Opentherm but it was only after I chatted to an Intergas installer on another forum that I found out that it has problems coping with multiple zones. I am still not sure why this is the case, as Honeywell has since told me that, for Opentherm control purposes, Evohome acts as a single zone (albeit, one with many inputs). That, left me with the Atag.

        I contacted Atag and they provided me with a list of their approved installers. I then had a chat with their technical department and they pointed me in the direction of an installer in Dursley, Gloucs. I suggest that you give Atag Technical Support a ring, If no joy, then PM me and I will give you my installer's details.

        Comment

        • Sean in Amersham
          Automated Home Jr Member
          • Jan 2017
          • 15

          #49
          A very useful reply, thank you. I have already contacted Atag UK and am waiting for their response. I am also waiting for Worcester Bosch UK and their installation engineers to reply to me but now the boiler is installed and some 9 months old they seem in no hurry to come back to me at this time.

          Comment

          • JCK
            Automated Home Jr Member
            • Dec 2015
            • 19

            #50
            I don't under stand the logic of the Spirovent to prevent corrosion . I understood (perhaps incorrectly) the corrosion is mostly by dissolved oxygen not by free air , Spirovent cannot remove dissolved oxygen. Also an inhibitor like Sentinel X100 can be dosed to excess without negative impact. For me an inhibitor would always make sense.

            Comment

            • HenGus
              Automated Home Legend
              • May 2014
              • 1001

              #51
              Originally posted by JCK View Post
              I don't under stand the logic of the Spirovent to prevent corrosion . I understood (perhaps incorrectly) the corrosion is mostly by dissolved oxygen not by free air , Spirovent cannot remove dissolved oxygen. Also an inhibitor like Sentinel X100 can be dosed to excess without negative impact. For me an inhibitor would always make sense.
              I think that Spirotech may disagree with your view. They warrant Spirovent as being capable of extracting 99.6% of dissolved air in water. I think that this is one for installers to argue about. Atag are happy as the water quality will be re-tested at every service, and they have issued a 10 year warranty on their boiler.

              Quote:

              With respect to heating water treatment with chemical agents the statement of the VDI 2035 is in contrast to the British Standard that such agents should only be used in limited cases by professionals with the necessary chemical education. According to VDI 2035 there is no need for chemical agents as in a well-planned operated and maintained system, with a favourable water quality, no damages caused by lime-scale and corrosion are to be expected.

              Unquote

              Edit: Just in case posters think that I have been sold a pup re corrosion inhibitor. This is an extract from the ATag Uk boiler installation manual:

              Fill the installation with mains cold water.

              In most cases, a heating system can be filled with water according to national standards for water and treatment of this water is not necessary.

              In order to avoid problems with the CH-installations, the quality of the fillling water has to meet the specifications mentioned in table 9.3.a:
              If the filling water does not meet the required specifications, you are advised to treat the water to such an extent that it does meet the required specifications.

              The warranty becomes invalid, if the installation is not being flushed and/or the quality of the filling water does not meet the specifications recommended by ATAG Heating Technology Ltd. Always contact ATAG Heating Technology Ltd in advance, if things are not clear or you wish to discuss any deviations. Without approval, the warranty becomes invalid.

              The document goes on to say that the use of corrosion inhibiters is at the owner's risk.
              Last edited by HenGus; 26 April 2017, 11:26 AM. Reason: Addtl info

              Comment

              • rotor
                Automated Home Guru
                • Aug 2015
                • 124

                #52
                Originally posted by HenGus View Post
                I have a 19 radiator/5 bed home with an unvented 250L OSO cylinder. The IS24 has replaced an Ideal Classic system boiler.

                I am still trying to get my mind around Opentherm and condensing boilers. At the moment, about 50% of the house is calling off and on for heat. The boiler currently has a flow temperature of 60C and a return temperature of 54C. There are considerably less zone temperature variations than was the case; no boiler cycling and the boiler itself is whisper quiet.

                Edit: I have just checked. Three zones and 10 radiators all at set temperature. The boiler has flow/return of 50C/49C. Pretty clever stuff.
                Hi HenGus, really appreciative of all the info you've been posting. I suspect I'm going to end up with EXACTLY what you've got. A couple of questions about your cylinder: did you choose it, or was it already there? Did you have any problems installing the EvoHome temperature probe? And if you chose it, was there anything specific about that brand (I'd never even heard of it), and how did you decide on the 250L size?

                Thanks again!

                Comment

                • bruce_miranda
                  Automated Home Legend
                  • Jul 2014
                  • 2307

                  #53
                  I personally am not sold on any Spirotech products. I even went through the hassle of swapping a Spirotrap with a Magnaclean Pro and the results are immediately apparent. The Spirotrap just isn't capable to catching and trapping everything. Important to consider this aspect especially if you are trying to run the system without any inhibitor. I too don't believe that the Spirotech thing can get rid of dissolved Oxygen, it's just a fancy air vent and nothing else.

                  Comment

                  • HenGus
                    Automated Home Legend
                    • May 2014
                    • 1001

                    #54
                    Originally posted by rotor View Post
                    Hi HenGus, really appreciative of all the info you've been posting. I suspect I'm going to end up with EXACTLY what you've got. A couple of questions about your cylinder: did you choose it, or was it already there? Did you have any problems installing the EvoHome temperature probe? And if you chose it, was there anything specific about that brand (I'd never even heard of it), and how did you decide on the 250L size?

                    Thanks again!
                    No problem sharing experiences. I have been sorting out a 'schoolboy' error. My installer's qualified helper (a heating installer in his own right) managed to fit the ABV cap/disc incorrectly. Yesterday morning, the HW BDR closed just as my first zone asked for heat. There was quite a bit of gurgling in the airing cupboard. Called my man who concluded that it was most likely pump cavitation so we discussed a variety of options. I should add that he is no great fan of running a boiler on a zone with just a couple of radiators.

                    He suggested that as a starter for 10, I should look at opening the ABV. Easier said than done, as the setting disc and cap appeared to do nothing. I have just taken the ABV apart, and I can see that the disc was not aligned with the actual valve setting. Easily done and easily fixed. I have just finished 30 minutes of online research about Atag pump head and flows, and I have concluded that the valve needs to be set at 2.2 so I will give that a go.

                    As to your question. I have an existing Oso Unvented 250L cylinder which doesn't have any ports for the HW kit. I discussed the problem with the Oso Technical Team and we concluded that the best bet was to open the electrical access panel and push the probe up at an angle under the insulating foam. It is held in place with a piece of an old plastic biro barrel. After 3 years it is still there. The HW kit itself is wired in series with the existing tank thermostat and top limit stat. You need to remember to turn the tank thermostat to a higher setting than the Evohome HW temp setting.

                    The kit itself throws up the occasional Loss of Sensor Comms Fault. I have discussed this with Honeywell and they do not consider it an issue.

                    Comment

                    • HenGus
                      Automated Home Legend
                      • May 2014
                      • 1001

                      #55
                      Originally posted by bruce_miranda View Post
                      I personally am not sold on any Spirotech products. I even went through the hassle of swapping a Spirotrap with a Magnaclean Pro and the results are immediately apparent. The Spirotrap just isn't capable to catching and trapping everything. Important to consider this aspect especially if you are trying to run the system without any inhibitor. I too don't believe that the Spirotech thing can get rid of dissolved Oxygen, it's just a fancy air vent and nothing else.
                      I think that this is a bit like 'which is the best boiler debate' ?. Often, it comes down to personal preferences and user/installer experience.

                      The VDI (2035) which I suspect Atag is obliquely referring to in its documentation relates to pressurised domestic heating systems. My reading of the VDI suggests that there is no actual requirement for either a filter or a de-aerator. - they are there to provide added protection to the boiler.

                      Comment

                      • bruce_miranda
                        Automated Home Legend
                        • Jul 2014
                        • 2307

                        #56
                        I think you won the best boiler debate, that's for sure.

                        Comment

                        • mtmcgavock
                          Automated Home Legend
                          • Mar 2017
                          • 507

                          #57
                          Originally posted by bruce_miranda View Post
                          I personally am not sold on any Spirotech products. I even went through the hassle of swapping a Spirotrap with a Magnaclean Pro and the results are immediately apparent. The Spirotrap just isn't capable to catching and trapping everything. Important to consider this aspect especially if you are trying to run the system without any inhibitor. I too don't believe that the Spirotech thing can get rid of dissolved Oxygen, it's just a fancy air vent and nothing else.
                          Couldn't agree more. The Magnaclean products are much better and effective at removing debris and sludge from a system. The Spirotech products are awful at removing dirt from a system, a Magnaclean that's been installed for a day could remove more dirt than a Spirotech could in a year.

                          You'd be mad to run a system without inhibitor, to me you are just asking for trouble.

                          Comment

                          • bruce_miranda
                            Automated Home Legend
                            • Jul 2014
                            • 2307

                            #58
                            The mandatory inhibitor addition is from an open vented era. It is a legacy which people aren't willing to give up in a closed looped system, which in theory should have no air or opening for air to get in.

                            Comment

                            • mtmcgavock
                              Automated Home Legend
                              • Mar 2017
                              • 507

                              #59
                              It's not just air that's in the system, it's the oxygen in the water that reacts with the steel in the radiators. In theory yes once a system is 'closed' no more oxygen should get in but even so on a good system it will loose pressure over time and have to be topped up. Topping the system up you are introducing fresh water with oxygen into the system, the inhibitor prevents the reaction from occurring. You also have to consider that poor quality radiators can rust and cause blockages in pipework and heat exchangers from fragments that have become free.

                              You'll also find your boiler manufacture won't warrant any parts damaged by not having inhibitor in the system, as it strictly says inhibitor must be added and is on your commissioning log.

                              Comment

                              • HenGus
                                Automated Home Legend
                                • May 2014
                                • 1001

                                #60
                                Originally posted by mtmcgavock View Post
                                It's not just air that's in the system, it's the oxygen in the water that reacts with the steel in the radiators. In theory yes once a system is 'closed' no more oxygen should get in but even so on a good system it will loose pressure over time and have to be topped up. Topping the system up you are introducing fresh water with oxygen into the system, the inhibitor prevents the reaction from occurring. You also have to consider that poor quality radiators can rust and cause blockages in pipework and heat exchangers from fragments that have become free.

                                You'll also find your boiler manufacture won't warrant any parts damaged by not having inhibitor in the system, as it strictly says inhibitor must be added and is on your commissioning log.
                                Atag does not ban the use of chemicals; however,.......

                                Should you wish to achieve the required water quality by using chemical additives, then this is your own responsibility. The warranty on the product delivered by ATAG Heating Technology Ltd expires, if the water quality does not meet ATAG Heating Technology's specifications or the chemical additives have not been approved by ATAG Heating Technology Ltd.

                                I think that a key factor here is that the boiler was designed primarily for use in The Netherlands. As I have indicated above, current standards in Germany for pressurised domestic heating systems no longer require inhibitors. They also allow for 5%/year replenishment with a full water test each year.

                                As one very knowledgeable installer (MSc) told me about his time in Germany, 'when you go to a heating trade show in Germany you end up speaking to Herr Doctor with a PhD in engineering; conversely, a U.K. Trade Show tends to have a very high proportion of salesmen'.

                                I should add that I was sceptical at first; however, my chosen installer was recommended to me by Atag Tech as he has installed 10s of their products (2 boilers in the last three weeks), and they have issued a 10 year warranty.

                                Ask me again if I was right in five years time.
                                Last edited by HenGus; 26 April 2017, 07:24 PM.

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