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Issue with solid fuel stove connected to Systemlink

24

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  • #32
    John T Carroll
    Closed Accounts Posts: 757 ✭✭✭John T Carroll


    Dtp1979 wrote: »
    You mentioned earlier about the culinder rupturing that would cause and explosion. How big of a rupture are you talking about? If the p&t valve failed or stuck, and only opened at say 110 degrees, would this cause a bang?

    No, because 110C is equivalent to only 0.5 Bar, the cylinder will only rupture if its design pressure is exceeded (normally by a factor of at least 1.5). I don't know what the design pressure of unvented SS cylinders is? but its probably > 6 Bar??. Re the cylinder rupturing, it could be of any size, obviously the smaller the better as it gives a sortof controlled release of the contents but boiler shells have sometimes opened up all along a welded seam and released all the boiler contents in seconds.


  • #33
    Dtp1979
    Registered Users, Registered Users 2 Posts: 12,922 ✭✭✭✭Dtp1979


    John T Carroll wrote: »
    No, because 110C is equivalent to only 0.5 Bar, the cylinder will only rupture if its design pressure is exceeded (normally by a factor of at least 1.5). I don't know what the design pressure of unvented SS cylinders is? but its probably > 6 Bar??. Re the cylinder rupturing, it could be of any size, obviously the smaller the better as it gives a sortof controlled release of the contents but boiler shells have sometimes opened up all along a welded seam and released all the boiler contents in seconds.

    Would you personally pipe a stove into an unvented cylinder?


  • #34
    John T Carroll
    Closed Accounts Posts: 757 ✭✭✭John T Carroll


    Dtp1979 wrote: »
    Would you personally pipe a stove into an unvented cylinder?

    If its against regulations, I think I dont have to tell you my answer, do you know if it is?

    In th FAS attachment below, page 39, "Interlinking of Solid Fuel to Automatic Boiler" its gives a nice schematic of the system, unfortunately it just shows the hot water cylinder as a "box", they do specifically state....."1 ins Unristricted Gravity Flow and Return on Solid Fuel" but strangley enough no specific mention of the hot water cylinder which is a bit baffling seeing that this publication is "Trade of Plumbing".


  • #35
    Dtp1979
    Registered Users, Registered Users 2 Posts: 12,922 ✭✭✭✭Dtp1979


    John T Carroll wrote: »
    If its against regulations, I think I dont have to tell you my answer, do you know if it is?

    In th FAS attachment below, page 39, "Interlinking of Solid Fuel to Automatic Boiler" its gives a nice schematic of the system, unfortunately it just shows the hot water cylinder as a "box", they do specifically state....."1 ins Unristricted Gravity Flow and Return on Solid Fuel" but strangley enough no specific mention of the hot water cylinder which is a bit baffling seeing that this publication is "Trade of Plumbing".

    Honestly im not sure if it is against regulations. I'm sure I read it somewhere that it is though.
    Aside from regulations, with your extensive knowledge of the subject, would you do it in your house?


  • #36
    Dtp1979
    Registered Users, Registered Users 2 Posts: 12,922 ✭✭✭✭Dtp1979


    Just had s look, and yes, it's against regulations.


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  • #37
    John T Carroll
    Closed Accounts Posts: 757 ✭✭✭John T Carroll


    Dtp1979 wrote: »
    Honestly im not sure if it is against regulations. I'm sure I read it somewhere that it is though.
    Aside from regulations, with your extensive knowledge of the subject, would you do it in your house?
    Dtp1979 wrote: »
    Just had s look, and yes, it's against regulations.

    Thanks for that but I will reply to your query, above.

    NO, I wouldnt connect a vented Solid Fuel Stove into a unvented Hot Water Cylinder in anyones house including my own for the following reasons.

    I am a great believer in Murphy's Law that if it can happen, it will.

    If you consider the unvented cylinder with an expansion vessel, the expansion vessel,s diaphragm can fail and more than likely will over a period of time, the P&T valve may start leaking and some bright spark in the house might just decide to blank it as you said previously so now you have a system with no expansion space and no safety valve. If the solid fuel isnt connected then its more than likely that the cylinder temperature will be around 60C and the expansion volume will be about 4.5 Litres which the pipework and entrained air in the system might take up without raising the cylinder pressure to dangerous levels and even if something did blow on the system, pipework etc then water at 60C will leak /spray around the place. On the other hand, if the solid fuel was connected then the temperature can and probably will rise to 105C/110C on occasions and the system will have to try and accomodate 15 ltrs expansion which quite possibly could raise the cylinder pressure to dangerous levels with the resultant leakage of water/steam at 100C.
    On the other hand if the solid fuel is connected to a vented cylinder then dangerously high pressure levels cant build up under any circumstances.

    Thats why I wouldnt do it, why take any risk when its avoidable.


  • #38
    gctest50
    Registered Users, Registered Users 2 Posts: 9,597 ✭✭✭gctest50


    Dtp1979 wrote: »
    Would you personally pipe a stove into an unvented cylinder?

    vaguely related,

    plugged T&P valve , stat disabled ~ bit like uncontrolled stove heat source

    launch velocity 900fpm





    they disable the stat (~much the same as uncontrolled stove heat source ) and get the pressure up

    the little house is built to building code




    lhKQj9v.jpg


  • #39
    John T Carroll
    Closed Accounts Posts: 757 ✭✭✭John T Carroll


    gctest50 wrote: »
    vaguely related,

    NO, not in any shape or form, to anyone out there who may have a system with a vented solid fuel stove connected to a unvented cylinder, you are not sitting on a time bomb as long as all the protections described above are in place plus the fact that all unvented cylinders now have a expansion relief valve as well.


  • #40
    Dtp1979
    Registered Users, Registered Users 2 Posts: 12,922 ✭✭✭✭Dtp1979


    John T Carroll wrote: »
    NO, not in any shape or form, to anyone out there who may have a system with a vented solid fuel stove connected to a unvented cylinder, you are not sitting on a time bomb as long as all the protections described above are in place plus the fact that all unvented cylinders now have a expansion relief valve as well.

    Only a few days ago I came across a brand new installation where there was no p&t valve fitted. In fact, there was nowhere on the cylinder to actually fit it which was strange to me.
    Another question,
    The above scenario but this time it's a bath tap with 3/4" piping that's opened by a child, the child hears rumbling and panics, runs away and leaves the tap open full. What would happen?


  • #41
    John T Carroll
    Closed Accounts Posts: 757 ✭✭✭John T Carroll


    Dtp1979 wrote: »
    Only a few days ago I came across a brand new installation where there was no p&t valve fitted. In fact, there was nowhere on the cylinder to actually fit it which was strange to me.
    Another question,
    The above scenario but this time it's a bath tap with 3/4" piping that's opened by a child, the child hears rumbling and panics, runs away and leaves the tap open full. What would happen?

    Again if one assumes a 300 Litre cylinder, mains fed, reduced to 3.0 Bar pressure and at a temperature of 110C (because no P&T v/v fitted) and also no antiscald valve fitted and someone opens a 3/4 ins bath tap. Again a mixture of water and steam at 100C will exit from the tap, because of the 110C temperature, 1.89% (461.56-419)/2257)*100) of the tap water will flash off as steam. If one assumes a flowrate of say 30 LPM then flash steam at a rate of 0.57 kgs/min (30*1.89%) will flow from the tap, the remainder will be water at 100C, this 0.57 kgs of steam can occupy a space of almost 1.0 M3 so would fill a small bathroom of 5M3 in about 5 or 6 minutes or so after which time the 300 Litres of hot water will be exausted and you will be left with a cylinder full of cold water at 3.0 Bar pressure.


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  • #42
    Wearb
    Moderators, Home & Garden Moderators Posts: 6,532 Mod ✭✭✭✭Wearb


    I have been following this thread and deliberately kept out of it so as not to drag it in another direction. Thanks John T Carroll for all your informative input on this subject. And dtp for your pertinent questions.

    In this area, I often find comparing it to the old style pressure cooker (with the jiggling weight) helpful.

    I do know that there is a perception out there that in the instance with the 3/4" bath tap -above- the whole contents of the cylinder would instantly turn to steam with catastrophic consequences. The fact that this doesn't happen (in this instance) is obviously no reason to ignore regulations, the reasons are explained in this thread.

    This thread will be of great help in increasing understanding of the issues and consequences.

    Thanks again.


  • #43
    John T Carroll
    Closed Accounts Posts: 757 ✭✭✭John T Carroll


    Wearb wrote: »

    I do know that there is a perception out there that in the instance with the 3/4" bath tap -above- the whole contents of the cylinder would instantly turn to steam with catastrophic consequences. The fact that this doesn't happen (in this instance) is obviously no reason to ignore regulations, the reasons are explained in this thread.

    That perception may be out there alright but at least it "errs" towards caution which is certainly no bad thing in itself, the ironical thing re the above scenario is that exactly the same thing would happen with a properly installed system, a vented solid fuel stove paired with a vented hot water cylinder, and while an antiscald valve in both instances would prevent potential scalding I think everyone is aware that antiscald valves just don't work very well with gravity flow systems, especially upstairs.


  • #44
    Wearb
    Moderators, Home & Garden Moderators Posts: 6,532 Mod ✭✭✭✭Wearb


    I often thought -with an unvented cylinder- that failed overheat stats on immersion heater was potentially a more immediate source of danger.


  • #45
    [Deleted User]
    Posts: 3,858 ✭ [Deleted User]


    John T Carroll wrote: »
    NO, not in any shape or form, to anyone out there who may have a system with a vented solid fuel stove connected to a unvented cylinder, you are not sitting on a time bomb as long as all the protections described above are in place plus the fact that all unvented cylinders now have a expansion relief valve as well.

    WOW, strong statement and one I totally disagree with. Tell me why unvented cylinder manufacturers instruct installers that no uncontrollable heat source can be connected to a cylinder?

    Would it surprise you that the main reason behind the introduction of UK G3 unvented cylinder safety regs was due to the amount of explosions that destroyed homes because of bad installation practices and homeowners capping pesky dripping safety valves.

    My day job is to promote safe unvented cylinder installations and as someone who has seen hundreds of installations I find it frustrating when a post like this appears because it strengthens the hand of those who don't wish to fit unvented cylinders safely.

    Go sit a G3 safety course which factors in human nature then lets have a chat about what is and isn't safe.


  • #46
    gctest50
    Registered Users, Registered Users 2 Posts: 9,597 ✭✭✭gctest50


    John T Carroll wrote: »
    NO, not in any shape or form, to anyone out there who may have a system with a vented solid fuel stove connected to a unvented cylinder, you are not sitting on a time bomb as long as all the protections described above are in place plus the fact that all unvented cylinders now have a expansion relief valve as well.

    and thats hy i put in "plugged T&P valve , stat disabled"

    gctest50 wrote: »
    vaguely related,

    plugged T&P valve , stat disabled ~ bit like uncontrolled stove heat source


  • #47
    gctest50
    Registered Users, Registered Users 2 Posts: 9,597 ✭✭✭gctest50


    John T Carroll wrote: »
    NO, not in any shape or form, to anyone out there who may have a system with a vented solid fuel stove connected to a unvented cylinder, you are not sitting on a time bomb as long as all the protections described above are in place plus the fact that all unvented cylinders now have a expansion relief valve as well.

    cos you get this kinda thing for real:
    Dtp1979 wrote: »
    Only a few days ago I came across a brand new installation where there was no p&t valve fitted.............?


  • #48
    [Deleted User]
    Posts: 3,858 ✭ [Deleted User]


    Wearb wrote: »
    I often thought -with an unvented cylinder- that failed overheat stats on immersion heater was potentially a more immediate source of danger.

    3kw vs 25-30 kW coil.

    As a manufacturers tech I'v never known it to be a problem but our immersion are limited to 65c.


  • #49
    [Deleted User]
    Posts: 3,858 ✭ [Deleted User]


    Instead of talking about explosions let's talk about more common day to day things, TP lifts due to stove being fitted, house gets flooded as TP pipework is not there or unsatisfactory, home owners house is destroyed home owner is scolded, where does that leave the home owner regards compensation, where does that leave the installer who thought he done a great job.


  • #50
    John T Carroll
    Closed Accounts Posts: 757 ✭✭✭John T Carroll


    Wearb wrote: »
    I often thought -with an unvented cylinder- that failed overheat stats on immersion heater was potentially a more immediate source of danger.

    I remember reading of a fatal accident in the UK (which I think triggered the fitting of Immersion overheat stats) in which a mother moved into rented accommodation with a child, the Immersion stat failed and water/steam started venting into the "plastic" header tank and started recirculating the contents, the tank then failed because of the high temperature and the contents of the tank came through the bedroom ceiling and the child died due to scalding.


  • #51
    John T Carroll
    Closed Accounts Posts: 757 ✭✭✭John T Carroll


    gary71 wrote: »

    My day job is to promote safe unvented cylinder installations and as someone who has seen hundreds of installations I find it frustrating when a post like this appears because it strengthens the hand of those who don't wish to fit unvented cylinders safely.

    I certainly don't want to appear to encourage this, far from it, I was referring to existing systems which may have a vented solid fuel stove paired with a unvented cylinder with all the safety devices operational. Are you suggesting that if someone had an arrangement like this and had it inspected by a competent person like yourself that it should be decommissioned and a vented cylinder fitted? or to go a step further, are these systems, where fitted, illegal in the UK?


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  • #52
    [Deleted User]
    Posts: 3,858 ✭ [Deleted User]


    I'v spent most of my working life in London doing a similar job promoting safety the one thing I'v always wondered is when I advise safe working practices in Ireland based on regs, manufacturers instructions etc... Why is it the risks needs to be quantified or opinionated upon? Is this something that starts at a young age ie... Don't touch the range you'll get burnt. But Mammy I'v touched the kettle before and that was much much worse.


    This is something that took me a while to get used to working here.

    What's wrong with just doing what the book says?

    Anytime a installer moves away from MI he/she takes full ownership of the installation and in some cases its not covered by their insurance because they were negligent.


  • #53
    Hitchens
    Registered Users, Registered Users 2 Posts: 8,100 ✭✭✭Hitchens


    guys, don't say waste pipe when you mean discharge pipe/line :cool:


  • #54
    [Deleted User]
    Posts: 3,858 ✭ [Deleted User]


    John T Carroll wrote: »
    I certainly don't want to appear to encourage this, far from it, I was referring to existing systems which may have a vented solid fuel stove paired with a unvented cylinder with all the safety devices operational. Are you suggesting that if someone had an arrangement like this and had it inspected by a competent person like yourself that it should be decommissioned and a vented cylinder fitted? or to go a step further, are these systems, where fitted, illegal in the UK?

    What do you deem as competent very few installers have sat a safety course and are unaware of potential risks posed.

    You don't get systems like you have here in the UK every cylinder is inspected by a building inspector before it can be used and the cylinder must complying with very strong safety regs.

    Any unvented cylinder connected to a uncontrollable heat source should be shut down until the installation meets MI this is due to the very real risk of water damage, scolding which is often not covered by home insurance.

    I come across lots of dangerous installation but home owners/ installers choose to ignore my warnings as they don't agree with me, imagine a 300ltr cylinder in a loft above a child's bedroom, no real weight support, fitted with plastic pipe from a stove, the safety pipe is plastic terminating above next doors kiddies play area and the complaint is the cylinder is making gurgling noises, scolding water coming out of the pipes and the next door neighbor is complaining about hot water spurting at them but all this happens when the stove is on. They blamed the cylinder.


  • #55
    Wearb
    Moderators, Home & Garden Moderators Posts: 6,532 Mod ✭✭✭✭Wearb


    gary71 wrote: »
    3kw vs 25-30 kW coil.

    As a manufacturers tech I'v never known it to be a problem but our immersion are limited to 65c.

    I did mention that I was talking about stat failure.

    The difference between coil and immersion output is only time. Over time the 3kw will heat a well insulated cylinder up just as much.
    I know in practice some hot water my be drawn off during this longer time. But that is not to be considered as a safety feature.


  • #56
    Wearb
    Moderators, Home & Garden Moderators Posts: 6,532 Mod ✭✭✭✭Wearb


    gary71 wrote: »

    What's wrong with just doing what the book says?
    What's wrong with questioning it? If we never questioned it we would still be standing on a flat earth that the universe revolved around. Still be using slides instead of wheels. Still be using standard efficiency boilers.

    That's why we question things. That's why manuals change.


  • #57
    [Deleted User]
    Posts: 3,858 ✭ [Deleted User]


    Wearb wrote: »
    I did mention that I was talking about stat failure.

    The difference between coil and immersion output is only time. Over time the 3kw will heat a well insulated cylinder up just as much.
    I know in practice some hot water my be drawn off during this longer time. But that is not to be considered as a safety feature.
    Forgive me, I was being a bit cheeky, I think every installation is unique and poses different risks no one worse than the other if the worest happens.


  • #58
    Wearb
    Moderators, Home & Garden Moderators Posts: 6,532 Mod ✭✭✭✭Wearb


    John T Carroll wrote: »
    I remember reading of a fatal accident in the UK (which I think triggered the fitting of Immersion overheat stats) in which a mother moved into rented accommodation with a child, the Immersion stat failed and water/steam started venting into the "plastic" header tank and started recirculating the contents, the tank then failed because of the high temperature and the contents of the tank came through the bedroom ceiling and the child died due to scalding.

    And that was a vented cylinder.


  • #59
    John T Carroll
    Closed Accounts Posts: 757 ✭✭✭John T Carroll


    Wearb wrote: »
    I did mention that I was talking about stat failure.

    The difference between coil and immersion output is only time. Over time the 3kw will heat a well insulated cylinder up just as much.
    I know in practice some hot water my be drawn off during this longer time. But that is not to be considered as a safety feature.

    I have great respect for the potential damage that a 3 KW Immersion can cause.
    If you take a 20 KW coil circulating water from say a oil fired boiler with the boiler stat set at 75C with a hysteresis of 10C, the maximum temperature of the water in the cylinder can the only be 70C, (75+65)/2, if the boiler stat fails then the max water temperature may reach 105/110C or whatever the hi limit Boiler stat is set at. If the stat fails on the Immersion and there is no overheat stat fitted then there is no limit to what the pressure/temperature may reach. If fitted to a vented cylinder, the Immersion is capable of generating almost 5 kgs of steam/hour or starting up a recirculation process in your plastic header tank with dire consequences when the tank fails.


  • #60
    [Deleted User]
    Posts: 3,858 ✭ [Deleted User]


    Wearb wrote: »
    What's wrong with questioning it? If we never questioned it we would still be standing on a flat earth that the universe revolved around. Still be using slides instead of wheels. Still be using standard efficiency boilers.

    That's why we question things. That's why manuals change.

    Manuals change in direct response to changing standards , Standards change in direct response to investigated incidents to prevent similar incidents even rare unusal incidents occurring again.


    It isn't the questioning I have a problem with, it's choosing to do other than the MI instructs because they don't agree with it, I love questions without them I wouldn't have a job, it's the arguments over safety I disagree with, installers often choose to use plastic pipe for cylinder installations as they choose to disagree with MI as the installer have deemed plastic pipe safe.


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  • #61
    John T Carroll
    Closed Accounts Posts: 757 ✭✭✭John T Carroll


    gary71 wrote: »
    Forgive me, I was being a bit cheeky, I think every installation is unique and poses different risks no one worse than they other if the worest happens.

    That's why Hazops are now done routinely by a team to arrive at a acceptable risk.


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