ProDave Posted May 28, 2018 Author Share Posted May 28, 2018 Yes indeed it is. I have seen it so many times using this sort of plastic bottle thing as the feed & expansion for a brine loop, mostly for GSHP's, I thought this is the way the professionals do it, so I will buy one and do the same. I never dreamed it would be so hard to identify and buy one. NEXT time I see one I will ask the installer. Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 28, 2018 Share Posted May 28, 2018 Chemical pot feeder chemical dosing pot still no result Phone call to follow tomorrow am as it's pissing me off now Link to comment Share on other sites More sharing options...
newhome Posted May 29, 2018 Share Posted May 29, 2018 (edited) This? https://lp-varaosaksi.fi/Expansion-tank-45-l Edited May 29, 2018 by newhome Link to comment Share on other sites More sharing options...
ProDave Posted May 29, 2018 Author Share Posted May 29, 2018 That looks suspiciously like it. @newhome wins the virtual hug. But at 91.76 € I may need to find it a bit cheaper........ Link to comment Share on other sites More sharing options...
newhome Posted May 29, 2018 Share Posted May 29, 2018 8 minutes ago, ProDave said: That looks suspiciously like it. @newhome wins the virtual hug. But at 91.76 € I may need to find it a bit cheaper........ Ha ha, I knew you’d say that about the price. On you go re finding it cheaper 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 29, 2018 Share Posted May 29, 2018 9 hours ago, newhome said: This? Son of a bi....... I hate second place. . ? Link to comment Share on other sites More sharing options...
newhome Posted May 29, 2018 Share Posted May 29, 2018 2 minutes ago, Nickfromwales said: Son of a bi....... I hate second place. . ? You were too slow! Maybe you could find a better price for Dave or maybe they stopped selling so many when this happened 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 30, 2018 Share Posted May 30, 2018 Yes, that looks a bit shat. I cant help noticing the closed fill valve on the top of that chuffing "expansion vessel". If it were a true ( F & E ) expansion vessel then it couldn't have a seal as it would need to be open to atmosphere. I still think these systems are sealed, not open pipe @ProDave, and would need to be told different / otherwise before carrying on down this route. That one pictured has clearly collapsed after being closed when the system was hot, and its been allowed to cool / contract. No sale sorry. A heating system need got be able to expand and contract freely, and an F & E tank is just so 'yesterday'. Does the antifreeze / inhibitor smell? Plus, you still need an overflow for that too so just a poor way to save a few bucks imo. £12 £8 £22 or all in a kit for The princely sum of £34 ! You could have bought that and fitted it by now Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 30, 2018 Share Posted May 30, 2018 You need the strap not the bracket for the lip-less smaller vessels. +£10 to go to the 18Litre version. Link to comment Share on other sites More sharing options...
newhome Posted May 30, 2018 Share Posted May 30, 2018 That photo was from an utter shitfest of a gshp installation. Makes my heating ‘installation’ seem almost normal! https://www.pistonheads.com/gassing/topic.asp?h=0&f=207&t=1095847 1 Link to comment Share on other sites More sharing options...
PeterW Posted May 30, 2018 Share Posted May 30, 2018 (edited) @ProDave an understanding of the theory of cubic thermal expansion is required here. For a constant pressure, water expands in a non-linear manner from 4c to 100c. If you know the expansion coefficient and the volumes, then you can calculate the size of the expansion vessel needed - bear in mind that most expansion vessels have a 3/2 expansion capability with them starting with 2/3 of the volume available to compress the bladder. Knowing that 10m of heating loop at 16mm holds 1.5 litres of fluid, and 10m of 22mm pipe holds 3.2m, you can calculate the volume of the system. I have 420m of loops, 24m of 22mm and a 60 litre buffer so a total of circa 132 litres of system volume. Based on this, at the Vmax of 65c and a start temperature of 8c , my system will expand from 132 litres to ~136 litres in total. That is assuming the pressure remains constant at 1.5bar. That will result in needing an 6 litre expansion vessel. At worst case I would need a 8 litre expansion vessel at 95c however at this point the ASHP, immersion and tank stats would have all shut down anyway which would have stopped anything calling for heat. In my system I've fitted an 8 litre tank and I'm using the ASHP 3 bar safety valve as the failsafe. If as a rule of thumb you use 1 litre of expansion vessel for every 100m of loop, and add 5 litres per 100 litres of buffer then you won't be far wrong. Edited May 30, 2018 by PeterW Typo Link to comment Share on other sites More sharing options...
ProDave Posted May 30, 2018 Author Share Posted May 30, 2018 A generous estimate of volume puts my system at 50 litres so I don't need much expansion room. Can the over pressure valve go anywhere? i.e outside on either the flow or return pipe to the ASHP so if it blew it would vent onto the ground thus removing one of my objections (need to vent the blow off) Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 30, 2018 Share Posted May 30, 2018 13 minutes ago, ProDave said: A generous estimate of volume puts my system at 50 litres so I don't need much expansion room. Can the over pressure valve go anywhere? i.e outside on either the flow or return pipe to the ASHP so if it blew it would vent onto the ground thus removing one of my objections (need to vent the blow off) Yup, hence my previous regarding putting it inside the ASHP with a pipe to ground. As you can't do that, just an insulated blow off with a street bend facing down and zero pipework will be A1. Rain based frost will be your enemy, possibly seizing the operational head of the PRV, but at those temps your pipework should be warm to hot anyhoo. Link to comment Share on other sites More sharing options...
ProDave Posted May 30, 2018 Author Share Posted May 30, 2018 So based on a total 50 litre volume, what size expansion vessel? Link to comment Share on other sites More sharing options...
PeterW Posted May 30, 2018 Share Posted May 30, 2018 11 minutes ago, ProDave said: So based on a total 50 litre volume, what size expansion vessel? What loop / 22mm feed lengths ..? Link to comment Share on other sites More sharing options...
ProDave Posted May 30, 2018 Author Share Posted May 30, 2018 42 minutes ago, PeterW said: What loop / 22mm feed lengths ..? I worked it out on 300M of UFH pipe and 30M of 22mm and that came to 50L Add a bit for 2 manifolds? Need to add the volume of the heatpump input coil on a 300L Telford tank. Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 30, 2018 Share Posted May 30, 2018 16 minutes ago, ProDave said: Need to add the volume of the heatpump input coil on a 300L Telford tank. ~ 21 L. Link to comment Share on other sites More sharing options...
PeterW Posted May 30, 2018 Share Posted May 30, 2018 1 hour ago, Nickfromwales said: ~ 21 L. Eh..??? 21 litres is what’s needed for the UVC not the coil and pipework..... @ProDave working from the coil spec I have, it’s 11.7 litres in the HP coil, 30m of 22mm and adding in the loops it’s circa 70 litres. At 90c that’s a 4.2 litre expansion vessel required so next standard one up is 8 litres which will be fine. Link to comment Share on other sites More sharing options...
ProDave Posted May 30, 2018 Author Share Posted May 30, 2018 If it gets to 90C it will be the first heat pump in history to do so. Link to comment Share on other sites More sharing options...
PeterW Posted May 30, 2018 Share Posted May 30, 2018 Its the failure scenario - you're right however you need to design for it hence the 8 litre one anyway (which is pretty small !) Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 30, 2018 Share Posted May 30, 2018 5 hours ago, PeterW said: Eh..??? 21 litres is what’s needed for the UVC not the coil and pipework..... Just going by what Telford said guv'ner, put away the cat 'o nine tails . Maybe they just gave me the current order I have in which has the larger coil in it. Link to comment Share on other sites More sharing options...
PeterW Posted May 30, 2018 Share Posted May 30, 2018 12 minutes ago, Nickfromwales said: Just going by what Telford said guv'ner, put away the cat 'o nine tails . Maybe they just have me the current order I have in which has the larger coil in it. I thought you meant the expansion vessel size @Nickfromwales..! So that’s interesting then though about the coil as the spec I’ve got says half that..! But it may be the standard coil not the HP coil ..? Even so, it makes squit difference as 8 litres is more than enough ... Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 30, 2018 Share Posted May 30, 2018 Yup and yup. Link to comment Share on other sites More sharing options...
ProDave Posted May 30, 2018 Author Share Posted May 30, 2018 9 hours ago, Nickfromwales said: or all in a kit for The princely sum of £34 ! You could have bought that and fitted it by now Almost got me. But "Does not post to Scottish Highlands". Aaaaaaaarrrrrrrrrrgggggggghhhhhhhhh Any reason not to buy this one? https://www.ebay.co.uk/itm/Altecnic-ERES-12-Litre-Heating-Expansion-Vessel-Sealed-System-Kit-EasiFit/221958453674?hash=item33adc139aa:g:OhYAAOSwwmlZiA0K 12L for only a couple of £ more and will post it here. Anything wrong with being bigger than needed? 1 Link to comment Share on other sites More sharing options...
Onoff Posted May 30, 2018 Share Posted May 30, 2018 12 minutes ago, ProDave said: Almost got me. But "Does not post to Scottish Highlands. Aaaaaaaarrrrrrrrrrgggggggghhhhhhhhh I've used ManoMano before no probs: https://www.manomano.co.uk/pulsation-dampening-tank-for-central-heating/eres-expansion-vessel-3875510?model_id=3875512 You'd have to check ref postage Link to comment Share on other sites More sharing options...
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