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Has this been carried out properly?

Discussion in 'Plumbing and Central Heating' started by JustAnotherSteve, 3 Mar 2021.

  1. JustAnotherSteve

    JustAnotherSteve

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    I'm hoping some kind soul might be able to comment if this workmanship has been carried out properly?

    Situation is: previously an open vented system which has been converted to a sealed system (the benefits of which I'm still unclear on). As such, an expansion vessel was positioned in the loft, and a prv above the boiler, leading to what I have discovered is the attached work having been carried out on the external wall behind the boiler.

    1. The partial foam covering will surely just disintegrate and/or blow off in strong weather? It just initially strikes me as a bit of a sticky tape and blu-tac approach?

    2. Where they have bored into the existing down pipe, there is some slight seepage which trickles down the outside of the down pipe as can be seen in the photo. Surely the seal should be tight?

    3. On a related note, we were quoted £295 for sealing the system incl expansion vessel, prv and 6mtr pump by the proprietor. The workers who attended did not see fit to install the 6mtr pump (as the sealing was done in preparation for a power flush), so do we know what a reasonable ballpark figure for the sealing should be in light of this?

    With thanks in advance,
    Steve


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  3. fixitflav

    fixitflav

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    It looks a botched job, they might at least have used the right size insulation, and used adhesive tape.
    That's the condensate pipe. But it sounds like the boiler wasn't changed, or was it? If not, no need to touch the condensate pipe.
    No idea about 3, I'm not in the trade.

    To add - it's definitely not right like that as it's at risk of freezing. Then the boiler will lock out and you've lost heating just when you need it.
     
    Last edited: 3 Mar 2021
  4. denso13

    denso13

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    It shouldn't be leaking but it doesn't look new. As above, was the boiler changed?
     
  5. Gasguru

    Gasguru

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    That looks like the old condensate pipework that was done when the boiler was installed...it's a bodge done at the time and even more so now the regs have been tightened regarding outside pipework.
    There's no need to seal a system just for a powerflush unless there's absolutely no way of clearing the feed or safety vent etc.
    Need more pics of the work done...show us the safety valve/filling loop/gauge and vessel.
    Safety valve should emerge through the wall normally although there are ways round that.
    Boiler make and model and what were the problems before this work.
     
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  6. ianmcd

    ianmcd

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    That is the condensate pipe and will require an air break, incase the downpipe blocks, it will damage the boiler
     
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  7. JustAnotherSteve

    JustAnotherSteve

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    Thanks all for the responses; it's much appreciated.

    Pardon my ignorance but when you say "unless there's absolutely no way of clearing the feed or safety vent etc", what does that mean specifically? We'd previously had two unsuccesful attempts to power flush, but by all accounts neither of those people seemed to know what they were doing (but happily took the money of course). We only went with a third power flush on the advice of an engineer who came to replace the heat exchanger and seemed to know a lot about the system we have (a thermal store, apparently, which was open vented). There was nothing in it for him in recommending we do so but he was able to recommend a company who he knew would be able to help, if anybody could. We went along with this latest company's advice to seal the system prior to a power flush because they recommended that would be beneficial, but since having unfortunately learned something about their lack of ethics (from one of their own staff, no less), we're now wondering if this was completely unnecessary and just a way to make money?

    The boiler is a Worcester Greenstar 15ri consdensing boiler. The story goes something like this:

    - 1st attempt at power flush maybe 4 years ago as some rads ineffective and some not working at all. The pipework is non-barrier 10mm microbore.

    - 2nd attempt at power flush maybe 2 years ago. Also unsuccessful.

    - Jan 2021: heat exchanger on boiler began to leak and was replaced.

    - Feb 2021: sealing of system and 3rd attempt at power flush, which has resulted in some rads now coming back to life and others absolutely flying. There are still some only lukewarm however, and 2 not working at all.

    Curiously the pressure gauge now reads zero (the boiler has been on for most of the day). I was led to believe it should be somewhere around 1 bar with fluctuation depending on whether the boiler is on or off. I wasn't expecting it to be zero.

    I'm now wondering if we have been led a merry dance with having the system (unnecessarily / unscrupulously?) sealed, and if it has now created a new issue. Although the pressure gauge reads zero, we still have CH and HW however. It's possible it may have been like this for a few days; I hadn't looked.

    Any further comments / advice most welcomed and appreciated. We have a 1-year-old and another on the way (there's only so much lockdown TV one can watch), so we're having to be cautious where/how to spend those pennies.

    Here are the "before" pictures of the airing cupboard and boiler:

    IMG-20210226-WA0000.jpeg

    IMG-20210226-WA0002.jpeg

    And here's the "after" shot of the boiler showing what I understand is the PRV:

    20210309_210348.jpg

    Comparing the two photos it looks like a second vacant hole has appeared in the wall towards the right. Does this new pipework / workmansip look like an ok job?
     
    Last edited: 9 Mar 2021
  8. Gasguru

    Gasguru

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    The white condensate pipework was done at the time of the boiler installation...and not very well.
    Outside pipework is prone to freezing and there is an added risk of the downpipe blocking from leaves etc causing rainwater to back up into the boiler.
    Have a look in any of Worcesters latest manuals to see the current thinking on condensate pipework routing.

    I can't see a reason for sealing the system.
    Powerflushing a microbore system is rarely successful...the bore is too small to get effective flowrates.
    However, in my experience most radiator poor performance is due to poor balancing of the rads ie. the flowrates to each rad are not set correctly or let-by on diverter/mid position zone valves, weak pumps etc.
    The pressure gauge should be set around 1 bar with the rads cold and rise no more than 2 bar with the rads fully hot.
     
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  9. JustAnotherSteve

    JustAnotherSteve

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    Thanks gasguru. So it looks like we have been duped down the route of needlessly paying to have the system sealed which has created a new issue of having zero pressure.

    - What are typically the worst case and best case scenarios of zero pressure?

    - Are we in any immediate/mid-term danger of there being zero pressure? Unfortunately we've lost confidence in raising it with the latest company who sealed the system as we feel they would use it as a means to extort even more money out of us.

    - Is it worth considering having the system reverted to an open vented arrangement as before? (Pros/cons?)
     
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  11. Gasguru

    Gasguru

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    The traditional open vented heating system has the small Feed and Expansion cistern in the loft.
    The height of the cistern creates a static pressure in the system (via the cold feed pipe) in order to bleed all air from the system.
    The cistern being open allows the water to expand back up into the cistern by a few % as the system heats up.
    In case of boiler malfunction the safety vent pipework (that runs up and dips over the cistern) allows steam to vent although modern boilers are not so likely to do that.
    Sometimes the safety valve pipe and feed pipe is combined but it's not ideal.

    Pros....
    The system doesn't need topping up.
    The system often operates under lower pressure than sealed systems.
    Little servicing (apart from the boiler) is required.

    Cons...
    A leak on the system can go unnoticed and will be continually fed by the cistern..this can be very damaging in the long run as fresh water is introduced causing corrosion.
    Cisterns are rarely installed properly and sludge/biofilms etc are often present in the cistern.
    A major leak will carry on until the system is drained.
    Risk of freezing if in the loft (which is normally the case to gain the height).

    An alternative is the sealed system...
    Air pressure (or nitrogen if the vessel is new) in the expansion vessel creates the static pressure to bleed air etc.
    The water expands back into the vessel and compresses the air allowing for expansion (and the pressure rises accordingly).
    A 3 bar safety valve is plumbed into the system to relieve excess pressure.
    A filling loop (flexible hose) is connected to pressurise the system to 1 bar cold (typical)
    A pressure gauge is fitted to monitor the pressure.

    Pros...
    The system operates under higher pressure and this can be beneficial to some heat exchangers (raised boiling point and less noise etc).
    A major leak is not so catastrophic.
    Perceived to be less likely to suffer from corrosion but this is a fallacy.
    A dry loft as all the components can be located in the living space.
    Pipework is more flexible as heights/positioning are not so critical.

    Cons...
    The gauge needs monitoring and the system needs topping up from time to time (but a good system only needs this every 6 months or so).
    Higher pressure so system has to have better quality valves/pipework.
    Expansion vessel needs yearly checking/re-inflating.


    It's swings and roundabouts....

    You should locate your filling loop and top up the pressure to 1 bar but you might want to have a quick check of the expansion vessel pressure first....read the FAQs.
    As for operating at 0 bar it all depends on the location of the boiler/pump etc.
    If the boiler is in the kitchen then the only real issue damage might be to the pump upstairs and risk of air ingress to the system.
    So in the short term may not be detrimental.
     
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  12. DavidLewis

    DavidLewis

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    Could you explain the "fallacy" bit please Gasguru? I have always been under the impression that a feed / expansion tank assures plenty of oxygen in the system water to feed the corrosion process. What am I misunderstanding? Thanks!
     
  13. Gasguru

    Gasguru

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    Heating systems and the quality of the water often boils down to luck but getting the basics right goes a long way.
    We come across 40 year old open vented systems with no inhibitors but spotless cisterns and pumps...but we also see small sealed systems with water like crude oil (that have had inhibitors).
    The rise and fall of the water in the cistern is perceived to allow air to be entrained in the water...obviously a bad thing and therefore sealed systems have been promoted as being better for corrosion resistance.
    But a low pressure open vented system will leak less over a high pressure sealed system that needs frequent topping up.
    And a well designed open vented system will have sufficient volume in the cold feed pipe that the interchange of water during expansion/contraction is minimised.
    A system with quality lockshield radiator valves (BS2767-10 but not Myson)/fittings/pipework etc with a quality inhibitor is key..
     
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  14. DavidLewis

    DavidLewis

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    Thanks for taking the trouble to share your experiences (y). It's very good to hear directly from someone like yourself who obviously has such a lot of practical knowledge.
     
  15. Terrywookfit

    Terrywookfit

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    If the pipework is Non Barrier as you say. Nothing will prevent internal corrosion........Except a re pipe!!
     
  16. Gasguru

    Gasguru

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    Just scrolled up...is it really non-barrier? That's not great.
     
  17. Harry Bloomfield

    Harry Bloomfield

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    I'll try to answer that one...

    An open vented system has a header tank (F&E tank) usually in the loft. The tank is open to atmosphere so if the surface of the water is agitated it can absorb air (oxygen), which can be circulated and cause steel radiators to rust. That only happens if the system looses water and needs the ball valve to open, to top the tank up, or make up for any evaporation from the tank.

    Another mechanism for introduction of oxygen, is via the vent pipe. This rises up from the heating system, then curves over at the top, to end in the tank just above the surface of the water. In a badly designed system, water from the system can be 'pumped over' - water will flow out of the end of the pipe, to flow back into the tank, which introduces air into the tank. This simply should not happen.

    Both open and sealed systems, each suffer from the same problem of rusting radiators, if they need regular topping up due to leaks or other water loss, so inhibitor is needed in both and the concentration of which needs to be maintained.

    My open vented system was installed 40+ years ago, has been checked at least annually by me. It is now on its third heat only boiler. At each replacement boiler, I have simply needed to drain the system refill and add inhibitor. Draining the system produces only perfectly clear water. On the last boiler replacement, I added TRV's all round and swapped out the original galvanised header tank for a new plastic version.
     
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