How to frost protect an Evohome system ?

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  • DBMandrake
    Automated Home Legend
    • Sep 2014
    • 2361

    #16
    Originally posted by bruce_miranda View Post
    I dont think that is a solution for the problem asked. The issue here is when there is pipework that might be outside a zone that might freeze but because all the zones are shut, there won't be any flow even if the boiler fired up.
    I think there should be a frost protection mode that fires the boiler and makes the water flow through the entire system for any amount of time before returning back to a previous setting.
    No it doesn't solve the problem at all. (Also I'm not sure how you bind a remote temperature sensor to a zone without an actuator ? I've been told before that this cannot be done in a multi-zone configuration, specifically by the Honeywell guys and Richard as well)

    My solution is low tech - I'm insulating all the pipes under the house. In answer to someones question earlier in the thread, no, most of the pipes are not currently lagged. The main 22mm manifold from the boiler in one corner of the house to a central underfloor location has that old fashioned fabric weave lagging but all the pipes from the manifold to the radiators are completely un-insulated, and some of the runs are quite long like 5 metres worth of 8mm microbore...one new run of 15mm PVC that an engineer installed for the living room when we first moved in turned out to be literally just lying in the dirt on the ground...

    I managed to finish about half of it last weekend before I was exhausted and sore all over from crawling around in the gravel and dirt in the crawl space. It's pretty tight in a few places, I managed to get stuck in a hole through an underfloor brick wall at one point but managed to free myself and discovered that I'm not claustrophobic as I first thought I might be, as I kept my cool and didn't panic. So by the time I'm finished every non gas pipe under the floor and in the loft will be insulated. I've even decided to insulate the main cold water supply pipe which runs in mid air about 10 metres through the crawl space from one side of the house to the other - if I'm going to do all these pipes I might as well be thorough then I can have peace of mind in the winter.

    There is one air brick on each side of the house that vents the crawl space although on the night that I was doing the work it was relatively warm (10 degrees) and still in the crawl space. But I could see on a very windy cold night that it could get quite cold under there due to the vents so the insulation should prevent any wind chill effects on the pipes.

    For the boiler I have a Drayton RTS3 that I'm going to install in the boiler closet to just fire the boiler to protect it. I'm not sure if I'll bother with the return pipe stat or not - as the boiler is in a small closet as soon as it is running it warms the closet right up so that should be enough to switch the 5 degree frost stat off again in a reasonable amount of time. Even on the coldest -6 degree nights we've had, the boiler closet has not gone below 18 degrees with the boiler running intermittently to maintain the bedroom temperature, and typically the room is about 25 degrees when the boiler is busy. If it was in a large room or garage then it would need a return flow stat to switch it off otherwise it would run continuously in a cold room as the waste heat from the boiler wouldn't warm a large room.
    Last edited by DBMandrake; 29 November 2016, 10:39 AM.

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    • bruce_miranda
      Automated Home Legend
      • Jul 2014
      • 2307

      #17
      Originally posted by Rameses View Post
      Ok use IFTTT command "IF outside temp drops below xxx then enable xxxx (can be a zone or quick action)" this will keep water flow.
      Which relys on an internet connection, so again not an acceptable solution.

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      • paulockenden
        Automated Home Legend
        • Apr 2015
        • 1719

        #18
        Just schedule a downstairs loo or similar for 10 minutes at 15 degrees at around 3am. On a normal night it probably won't even kick in, but if it's really cold this should be enough to keep things moving.

        It tends to be outdoor pipes (e.g. garden taps) that freeze overnight. Indoor pipes (even in lofts and crawl spaces) will typically freeze only when a house has been left unheated across a number of very cold days. That's why people return from holidays to find burst pipes, but it almost never happens with a lived-in house.

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        • DBMandrake
          Automated Home Legend
          • Sep 2014
          • 2361

          #19
          Originally posted by paulockenden View Post
          Just schedule a downstairs loo or similar for 10 minutes at 15 degrees at around 3am. On a normal night it probably won't even kick in, but if it's really cold this should be enough to keep things moving.
          Again, this seems to be missing the point. If only one room comes on most of the pipework under the floor will still not flow and remain cold.
          It tends to be outdoor pipes (e.g. garden taps) that freeze overnight. Indoor pipes (even in lofts and crawl spaces) will typically freeze only when a house has been left unheated across a number of very cold days. That's why people return from holidays to find burst pipes, but it almost never happens with a lived-in house.
          Perhaps so, but I think the best (albeit most awkward and uncomfortable) solution is to simply insulate all the pipes. At least I should see some minor energy savings from that as well, and I only need to do it once.

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          • paulockenden
            Automated Home Legend
            • Apr 2015
            • 1719

            #20
            Originally posted by DBMandrake View Post
            Again, this seems to be missing the point. If only one room comes on most of the pipework under the floor will still not flow and remain cold.
            What if you schedule the rad at the far end of the pipe run?

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            • Rameses
              Industry Expert
              • Nov 2014
              • 446

              #21
              Originally posted by bruce_miranda View Post
              Which relys on an internet connection, so again not an acceptable solution.
              Why is this not acceptable?
              getconnected.honeywell.com | I work for Honeywell. Any posts I make are purely to help if I can. Any personal views expressed are my own

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              • DBMandrake
                Automated Home Legend
                • Sep 2014
                • 2361

                #22
                Originally posted by paulockenden View Post
                What if you schedule the rad at the far end of the pipe run?
                No use. There isn't a far end of the pipe run as such as its not laid out in a ladder configuration with short runs to each radiator.

                For the downstairs there is a main 22mm trunk feed about 4m long from the boiler to a central underfloor location near the hallway, from here it branches off in every direction to each individual radiator in a kind of a star configuration with all pipes except the living room being 8mm microbore. So no matter which individual radiator comes on only the 22mm trunk and the pipes to that one radiator will get hot, all the runs to the other radiators will stay cold, and some of them are as much as 5 metres.

                Annoyingly I also discovered when I was down there that when the guys converted the living room from single end feed 8mm to more modern 15mm both end feed (using PVC) they didn't remove the old pipes - they just squeezed and soldered the end of the old 8mm microbore and literally left it hanging there in mid air. So I have a 2x5 metre dead end run of microbore that is still tapped back into the main trunk that never flows and is therefore more vulnerable to freezing than the ones that are operational.

                If I'd known that was there when I did the drain down recently I would have got under there and snipped that off right back near the trunk and soldered a couple of caps over the stubs... but because it's still there and connected (and thus able to burst and leak) I decided I'd have to insulate the dead end runs just like all the other pipes! Grr... next drain down they will be getting surgically removed.
                Last edited by DBMandrake; 29 November 2016, 01:07 PM.

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                • guyank
                  Automated Home Sr Member
                  • Sep 2015
                  • 73

                  #23
                  Originally posted by DBMandrake View Post
                  My solution is low tech - I'm insulating all the pipes under the house.
                  This was my solution to the exact same problem. We had underfloor insulation fitted last summer and I was concerned that we would return to frozen central heating pipes under the house when we returned from being away for a week. I asked the guys who were doing the insulation to do it and it was only about £25 if I remember correctly. Much better than crawling round there doing it my self. Unfortunately they convinced me that the fabric insulation that was wrapped around half the pipework was sufficient. At some point I'll probably end up doing that myself.

                  Incidentally, I've set the 'Away' quick action to 10 degrees for all zones and use that instead. The gas usage doesn't seem to be that huge and it means there is less chance of freezing and the house takes less time to come back up to temperature.

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