difference between a condensing boiler & a Combination

Discussion in 'Plumbers' Talk' started by mesiko1, Feb 12, 2006.

  1. mesiko1

    mesiko1 New Member

    Are the filling and draining proceedures the same for a condensing boiler & and a Combination boiler
  2. chris@vietec.com

    chris@vietec.com New Member

    Many people are getting confused by this, a combination boiler is a condensing boiler, it is also a system boiler,to keep it simple you get two types of boilers, a system boiler, which runs the heating and heats hot water via a store, then you get a combination boiler, which runs the heating and heats hot water via a heat exchanger within the boiler, both these boilers can be of the condensing range, the condensing bit is to do with the boilers been more efficient
  3. Water Systems

    Water Systems New Member

    Many people are getting confused by this, a
    combination boiler is a condensing boiler,

    It seems many are confused inc you.

    A <u>combination boiler</u> is a combination of CH and DHW on one box. It can be sealed, open vented, condensing or non-condensing.

    A Condensing boiler is a high efficient boiler that requires a drain for the condensate. It can be a open vented, sealed or in a combination design.

    <u>System boilers</u>, generally, are for sealed systems, having the expansion vessel, pump, and sealed system controls inside the white box giving excellent packaging. They can be non-condensing or condensing.

    Most combi boilers are system boilers with a water section added, giving the ultimate packaging or all inside one box and no tanks or cylinders.

    <u>Heating Boilers</u> tend to be basic boilers with no pump, expansion vessel, etc. They can be open vented using an F&E tank or sealed with external expansion vessel, pump, etc.
  4. spur99

    spur99 New Member

    sorry to sound dumb but can you explain how an open vented combi works?
  5. Water Systems

    Water Systems New Member

    sorry to sound dumb but can you explain how an open
    vented combi works?

    It doesn't have an integral sealed pressure vessel and uses an F&E tank. There are few models left, if any, that can be open vented - I think ECO-Hometec have one. The top makers will allow variations to installation if you ciontact them. The mass maket makers tend not to deviate from the manual, as the tech kid on the phone probably will not understand too much about it.

    Many combi's have the same heat exchanger as heating and system boilers - one type through the range. If you see a heating boiler with the same heat exchanger as a combi, you will be right in assuming it can be open vented if the pressure vessel failed. Ringing the makers can conmfirm this. However some don't like it as it increases the call rate to the tech dept. Any sensible engineer looking at the boilers could safely convert a sealed to a open vented.
  6. spur99

    spur99 New Member

    would you just connect the f&e tank to the c/h return pipe instead of the mains filling loop?
  7. Water Systems

    Water Systems New Member

    would you just connect the f&e tank to the c/h return
    pipe instead of the mains filling loop?

    Whatever the makers say. If they say no, and you know of a vented version using the same heat exchnager then follow that. They makers may not support it if it is connected that way as it is not in their manual.

    A friend of mine has his integral pressure vessel go and the pasrt cost was astronomical. No place for an external vessel near the combi, so I took the feed and expansion pipes off the flow, with the tee both together and the feed towards the boiler and up to an F&E tank in the loft. Has worked a treat ever since. Every 4 years he tops up the F&E tank with X-100.

    CAUTION: You have know what you are doing though
  8. chris@vietec.com

    chris@vietec.com New Member

    Water Systems, do not criticise my replies, I was merely explaining to the poster that a combination boiler is also a condensing boiler, as in a condensing combination boiler, many people seem to think you get a combination boiler then you can also get a condensing boiler, as if they are two different things, I like to keep my answers short and to the point, I do not like writing a 50 page technical paper as you seem to do, to answer a simple question, I also do not mention non-condensing boilers, as it is now law to fit condensing boilers, or did you not know, I'm a responsible installer and I always fit condensing boilers, I do not go around looking for excuses not to, I also never fit open vented boilers, as I see this as going backwards with technology, why drag heavy objects accross the floor when the weel has been invented.
  9. chris@vietec.com

    chris@vietec.com New Member

    <u>Heating Boilers</u> tend to be basic boilers with
    no pump, expansion vessel, etc. They can be open
    vented using an F&E tank or sealed with external
    expansion vessel, pump, etc.

    So you like to criticise well so can I, your point above, heating boilers, tend to be basic boilers with no pump, expansion vessel, "Tend to be", wel der!!, if they had a pump and expansion vessel they would be a system boiler wouldn't they.
  10. Water Systems

    Water Systems New Member

    Water Systems, do not criticise my replies,

    It was wrong - simple as that. A poor explanation. Some thing from you like, thanks Water Systems for doing that would be nice.

    I was merely explaining to the poster that a
    combination boiler is also a condensing boiler,

    It isn't..read my post on that. That is why I posted a proper explanation.
  11. Water Systems

    Water Systems New Member

    tend to be basic boilers with
    no pump, expansion vessel, etc. They can be open
    vented using an F&E tank or sealed with external
    expansion vessel, pump, etc.

    So you like to criticise well so can I, your point
    above, heating boilers, tend to be basic boilers with
    no pump, expansion vessel, "Tend to be", wel der!!,
    if they had a pump and expansion vessel they would be
    a system boiler wouldn't they.

    You really need to concentrate and read. I explained quite simply the differences of all the boilers types (except the differences of combis, as there are various types of combis: stored primary water, store secondary water, infinately continuous, CPSU). I have seen some so-called heating boilers that had a pump inside and sealed system components - some makers have their own interpretation on this, however a heating boiler is generally what I described.
  12. chris@vietec.com

    chris@vietec.com New Member

    You need some training Water System, are you trying to say that a combination boiler is not a condensing boiler, because it is, try looking at the Vitodens range, last time I looked they had condensng combination boilers, along with Atag, Geminox. Glowworm, Vaillant etc, all of them have condensing combination boilers.
  13. Water Systems

    Water Systems New Member

    You need some training Water System,

    I do?

    are you trying
    to say that a combination boiler
    is not a condensing boiler,

    I am not. Read what I wrote it was quite clear. There are non-condensing combi boilers and condensing combi boiler - go to Wickes and they have the two on display. That is simple, not difficult to understand. Read my explanation again.
  14. MaryWhitehouse

    MaryWhitehouse New Member

    Now then ladies.. calm down.

    To the original poster.

    In simple terms.

    A combi boilers heats the water when you turn the tap on. No hot water is stored. So you can never run out of hot water.

    The rest of the boilers (you'll probably hear them called various different names) have a tank of hot water. So once you've filled the bath it make take some time for the boiler to heat up another tank for you.

    All boilers can be condensing or non condensing. A condensing boiler is just more energy efficient. As has been mentioned, the law is that new boilers should be condensing type, unless you have a good reason not to.

    Note: The above is a simplification of the descriptions.
  15. chris@vietec.com

    chris@vietec.com New Member

    The original question asked if the draining and filling was the same for a combination boiler and a condensing boiler, leading me to believe that the poster thought that you had either a condensing boiler OR a combination boiler, my answer simply was saying that a combination boiler is a consensing boiler as in a Condensing combination boiler, some people seem to think that you get a system boiler, combination boiler and a condensing boiler as if it is a completely different boiler, I was trying to explain in simple terms that a Combination boiler is condensing and that a system boiler is condensing, it is not a different type of boiler.
  16. Water Systems

    Water Systems New Member

    Now then ladies.. calm down.

    To the original poster.

    In simple terms.

    A combi boilers heats the water when you turn the tap
    on. No hot water is stored. So you can never run out
    of hot water.

    No.:-( Many store hot water. Infinately continuous conmbis do not store hot water. Some stored water models have high flowrates and when the store is exhausted drop down to infinately continuouse flow rates (what water boiler can heat up instantly), so the best of both worlds as you never run out of hot water. See the Alpha CD50.

    The rest of the boilers (you'll probably hear them
    called various different names) have a tank of hot
    water. So once you've filled the bath it make take
    some time for the boiler to heat up another tank for
    you.

    All boilers can be condensing or non condensing. A
    condensing boiler is just more energy efficient. As
    has been mentioned, the law is that new boilers
    should be condensing type, unless you have a good
    reason not to.

    Yep.

    Note: The above is a simplification of the
    descriptions.

    Ultra simple to say the least. :)
  17. chris@vietec.com

    chris@vietec.com New Member

    Water System you always seem to want to over complicate matters, the question was answered by my post,nice and simple, you come on and start banging on about storage combis, this,that and the other and over complicate the situation, all us installers kow all the different types of boilers availiable, if a poster wanted to know all the boilers availiable they would ask, this poter did not he merely seemed confused over a combination boier been different to a condensing boiler to fill and drain, my answer explained.
  18. chalky

    chalky Member

    water systems you explain well....chris not so well. I don't think you should take it personal chris!
  19. Arpas

    Arpas New Member

    my answer simply was
    saying that a combination boiler is a consensing
    boiler as in a Condensing combination boiler, some
    people seem to think that you get a system boiler,
    combination boiler and a condensing boiler as if it
    is a completely different boiler, I was trying to
    explain in simple terms that a Combination boiler is
    condensing and that a system boiler is condensing, it
    is not a different type of boiler.

    And if you had said 'a combi boiler can be condensing or not, and a system boiler can be condensing or not' then your explanation would have been short and correct, as far as it went.
    To say a combi boiler is a condensing boiler is wrong. And it left the way open for the resident pedant to demonstrate his 'expertise'.
  20. blahblah

    blahblah Guest

    Good old WS making friends again!

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