Combi or Unvented for a 6 bed house?

Discussion in 'Plumbers' Talk' started by AlexJ, Oct 26, 2015.

  1. miss pickle

    miss pickle Well-Known Member

    Even Google isn't listening to you nowadays smiley-laughing025.gif
  2. chippie244

    chippie244 Super Member

    Or turn the monitor on:D
  3. Ryluer

    Ryluer Well-Known Member

    Nah. If the best they can do is lash in an unvented then I'd rather stick with google.
  4. miss pickle

    miss pickle Well-Known Member

    I think old walter was trying to turn miss p on earlier chips shy-1.gif I didn't fall for it.

    I'm sticking with kiab ;)

    I haven't noticed AT ALL that kiab does not speak to me now. Ive got so used to him blowing hot and cold :rolleyes:
  5. Ryluer

    Ryluer Well-Known Member

    He might be hard up but he ain't desperate. [​IMG]
  6. miss pickle

    miss pickle Well-Known Member

    I will have you know I'm a very attractive woman with a good heart :D and I cook a delicious roast :)
  7. Rulland

    Rulland Screwfix Select

    Pictures!.................of the roast obviously............:D
  8. miss pickle

    miss pickle Well-Known Member

    You first :) unless you are married :rolleyes: coz I ain't going through that again :p
  9. miss pickle

    miss pickle Well-Known Member

    Ohhhh the roast :D sorry :oops:
  10. That sort of glib remark is pointless.

    I don't know how dangerous these cylinders are, so that's why I'm asking. But this doesn't help either;

    1. If any of these cylinders are played about with they can explode.
    2. 20 years down the line without a service (few know about servicing), the risk of explosion is high.
    3. If they are poorly made they can explode.

    1. Of course they can. Anybludything that's played about with can explode. Including one's knob.
    2. High? What the hell does 'high' mean? Very likely? More than 50%? 20%? What? 'High' is currently meaningless.
    3. As can pretty much anybludything. A lighter. A boiler. A can of beans.

    You are going to have to do better than that, Walt. Your comments and claims need to be backed up with more than flippant remarks.

    How about answering my previous post, which was a genuine attempt to get some serious answers?
  11. Walt Systems

    Walt Systems Member

    You mean 1 years experience repeated 20 times. :D:D
    Last edited: Nov 2, 2015
  12. Walt, any idea what the causes of these exploding cylinders were? I mean, is there a single recorded example of a correctly-installed cylinder going 'bang'?

    If not, then surely it comes down to incompetent installation - a bit like a leaking gas fire, or a badly installed flue on a boiler, or the car's brake pads fitted without their retaining clips; they can kill, but it ain't the appliance's fault. It's the twit who dun the work.

    My Q - and it's an honest one 'cos I really don't know - are these unvented cylinders in themselves inherently dangerous?
  13. Walt Systems

    Walt Systems Member

    The risk of explosion 20 years after install without a service is far higher. Few are serviced and when serviced the full range of checks is not done to ensure the safety controls work - it take a lot of time. Would you buy a poorly made gun that could blow up in your face after about 50 shots? There are many poorly made unvented cylinders about. We are a waiting time bomb.
  14. Walt Systems

    Walt Systems Member

    You never knew what a Torrent was. Try a Google. You have to know the products available and what they offer. Not con customers with only unvented cylinders and system boilers to get a good mark up on. Jobbing plumbers are a curse.
  15. Oh Walt - you are letting me down, man :(.

    Again, that is a meaningless reply.

    Of course any appliance that ain't serviced regularly is more likely to go faulty - explode even - after 20 years. I'm about to do some ironing, and my iron has never been serviced. You got me all nervous now... :rolleyes:

    But does that apply to a correctly installed unvented cylinder? I need an answer to that. All the ones (the very few...) that have blown up, why did they do so? Lack or servicing? Or an incorrect installation?

    Why the analogy with the gun?! I'd suggest such comments act against your arguments rather than support them.

    Anyways, it must surely be known what caused these half-dozen cylinders to go 'bang'? Any idea?
  16. Walt Systems

    Walt Systems Member

    I gave the one in Hampshire. The thread from 2009 highlights gushing steam in the first post.

    Incompetent installation on a vented thermal store will not take the roof off. Getting it? Unvented cylinders in themselves are inherently more dangerous as they store pressurised hot water. Get this two wrongs make a right in pointing to a badly installed gas fire. A gas fire can go bang and so can a cylinder so all is fine. Yerrrrr :( Think of the lowest risk at all times.

    I had a house which had a boiler in the kitchen. The meters were in the detached garage. I moved the boiler into the garage attic in an insulated cupboard. The flow and return went in an insulated pipe under the frost line with added insulation on top of the pipe to the house from the garage. I converted the 200 litre cylinder to a thermal store using a plate heat exchanger. The boiler only heated the thermal store directly with the pump in the garage. Much safer and space liberated in the kitchen and no noise. If something went wrong with the boiler it does not happen in the house. Think safety. If you can go the extra yard do it!

    A vented Gledhill Torrent DHW only thermal store is around £900. Many companies make them. The reason the jobbing plumbers do not fit them is that they are ignorant of the advantages and have zero experience of them.
  17. Of course I agree that an unvented cylinder is more dangerous than a vented type.

    But I'm still asking just how mush more dangerous?

    And of course one would try - within reason - to make things as safe as possible, allowing for the simple fact that almost everything is a risk to some extent. Are you suggesting that everyone should move their boilers out to their garages like you did?

    At some point you have to say "That just ain't worth it for the teeny-tiny added increase in safety."

    So that is why I'm asking - what makes the unvented cylinder actually unsafe?

    Yes, if they blow up it'll be a much bigger bang than a vented cylinder, but what will make them 'blow up'?

    How can you justify your 'ticking time-bomb' remark?
  18. Ok, ok, ok...

    You win :(

    I've chust looked up the Gledhill and watched a couple of vids. I'm having that in my next hoosie :)
  19. Walt Systems

    Walt Systems Member

    If something can lift the roof then that is far more dangerous than an equivalent that does not. You fit the one with least risk. That is easy to figure out. In the likes of Holland they have a boiler in a room/cupboard that is accessed from outside. They think safety and convenience from the outset. They keep the big box with fire in it out of the house.

    I am suggesting they move boilers out of the house if possible. And I am suggesting installers do the same.
  20. Walt Systems

    Walt Systems Member

    Gledhill modulate the DHW pump to maintain the DHW temp. The Torrent has been updated.

    I would have vented thermal store. Have the radiators off the thermal store via a coil. The ignorance on thermal stores by so-called "professionals" is apparent. Quite unbelievable. If you have a thermal store with the water in the cylinder not running through the rads sludge does not occur. Sludge only happens when the ferrous from the rads dumps the magnetite into the store. Standing losses on unvented cylinders and thermal stores are about the same.

    The best way is to have a thermal store cylinder with the following:
    1. Vented with maybe a header tank just over the cylinder - can be remote in loft.
    2. Heated directly via a vented boiler.
    3. Radiators taken off the store via coil - the rad water is separate to the stored water, hence no sludge.
    4. A second solar coil can be incorporated if solar is wanted in the future.
    The stored water will circulate only only through the boiler and DHW plate heat exchanger. The only ferrous is the pump, This can be a brass pump (at extra cost) and then eliminate all ferrous in boiler and store. The so-called "professionals " think all stores create sludge which is nonsense if it is done properly - isolated the CH rads water from the store water. Just the odd 1 litre of X-100 poured into the store every 3 to 4 years just to be sure, but if not put in there will be no problem. The X-100 will lubricate the pump and protect from a small amount of ferrous in the pump. No sludge will enter the boiler's heat exchanger which gets backed on, keeping the boiler working at full efficiency all of it long life. The boiler can be a cheaper simple model.

    The rad circuit can have a sealed system kit fitted with its own pressure vessel to prevent air ingress. Have the rad circuit fed by a modulating Alpha or Smart pump. Then TRVs on all rads and no wall stat, giving independent temperature control of each room. If another zone is needed then add another pump with check valves on each circuit.

    The boiler can be very big giving a super quick recovery. For e.g., if you get a cheap deal on 50kW vented boiler go for it, as long as the flow and return pipe sizes from the boiler to the store are sized OK. A gas meter is capable of 62 kW. The bigger the boiler the smaller the thermal store and the lower the standing losses, also savings using a smaller store. A thermal store cares not a jot what size the boiler is. Put a large boiler on a small rad circuit and you have big boiler troubles. The same with a small coil in an unvented or vented cylinder. The thermal store is a fantastic buffer as all aspects operate independently. The boiler will always be running at its most efficient with full flow through its heat exchanger. It heats up the cylinder in one long efficient burn. Boilers really do last when only heating thermal stores being in the ideal hydronic environment. They rarely cycle if at all.

    You can also fit a high kW immersion(s) as a backup, for CH & DHW.

    Beware of so called "professionals" who say a Vaillant and unvented cylinder is the only way to go. No doubt these "professionals", who specialise in drains, will come back with ad hominem attacks, with technical substance and experience lacking. Wait and see. It is hilarious to read. Guaranteed to happen. :)

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