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  1. #1

    Confused Glycol and Glycol-Water pumps for central heating help!!

    If you have to use water-glycol for central heating in a place where the minimum temperature is minus 7 deg celcius,

    I have some questions:

    1. How do you decide the glycol-water mixture ratio so that the water in the pipes does not freeze? For -7 celcius ambient.

    2. What would be the heat carrying capacity of the water-glycol mixture as determined above? How to select the radiator size?

    2. What pumps do you need for glycol pumps and glycol-water pumps? What variables are required to select these pumps?

    (Glycol pumps for glycol makeup circuit; glycol-water pumps for circulating hot glycol-water mixture in the building, for heating the building, using strategically placed radiators thru which the water-glycol loses heat to the conditioned space.)

  2. #2
    Join Date
    Jun 2011
    Location
    Glenrothes, Scotland
    Posts
    45
    Well, firstly I should say that I'm talking about how these things are done here in Scotland, but the principals are the same. The Glycol water mixture should be determined based on the recommendation of the glycol/inhibitor manufacturer. In our case we regularly get winter temperatures of down to -20c. We usually add between 25-30% system volume as inhibitor. This has 3 major advantages. Firstly it provides freeze protection, secondly it provides good corrosion protection and thirdly it inhibits bacterial growth. We assume the heat carrying capacity to be the same as bare water (4.186 joules/gram deg C). Radiator sizes can only be chosen when you know the heat loss of the space to be heated. The pipe sizing must also be calculated based on the heat requirement of the building. (You could fit the biggest rad in the world, but it will only provide as much heat as the pipe to it allows!) We don't tend to use make up units, we manually add inhibitors.so I cant advise on make up pumps. The system pumps themselves must be capable of overcoming the resistance of the index circuit. This is the pipework circuit with the highest resistance in the system. They must be capable of supplying the correct flow rate to achieve delta t at the radiators and the appliance (boiler).

  3. #3
    Join Date
    Mar 2006
    Location
    Denver/Boulder
    Posts
    2,219
    BlackHawk,

    Let me translate the for you.

    It's complicated.

    If you are a bonafide pro, then you need more training in this area. Get your post count up and you will be welcomed into the open arms of the professional community here at HVAC-TALK. We can help you help yourself.

    If you are not a pro, then sorry we cannot help you engineer your system. DIY is not permitted here for many reasons. Bastardly,Dastardly lawyers are one. We may be able to help you find the right contractor that DOES know how to do these things correctly.

    If you happen to be in Glenrothes, Scotland then I would suggest you contact Boabcelt, I can already tell that he is a fine man indeed.

    As you are most likely elsewhere, we will have to consider other options.
    What lies behind us and what lies before us are small matters compared to what lies within us.


    Two pressures, four temperatures = SUCCESS!


    Boulder Heating Contractor


    For Consumers:

    For HVACR Professionals:


  4. #4
    Join Date
    Jun 2011
    Location
    Glenrothes, Scotland
    Posts
    45
    Aw shucks man, you're making me blush! Is it right enough that guys can't DIY a heating system in the U.S.? In Scotland you can do pretty much everything apart from the gas work/flueing without being registered. Sort of. The law allows a homeowner to carry out gas work 'if the person can prove competence' and is 'not working for reward'. The phrase can of worms springs to mind.

  5. #5
    Join Date
    Mar 2006
    Location
    Denver/Boulder
    Posts
    2,219
    Quote Originally Posted by Boabcelt View Post
    Aw shucks man, you're making me blush! Is it right enough that guys can't DIY a heating system in the U.S.? In Scotland you can do pretty much everything apart from the gas work/flueing without being registered. Sort of. The law allows a homeowner to carry out gas work 'if the person can prove competence' and is 'not working for reward'. The phrase can of worms springs to mind.
    LOL

    What canna' say man!! The bonnie lads of Scotland are less prone to blowing themselves up and having their relatives sue assorted websites.

    ... which is not to say that a Scotsman would have any fear of blowing himself up! He just wouldn't direct his relatives to sue anybody.

    You will have mail shortly (if you have an Email in your profile) if not, please correct.

    correction- you have no email in your profile. If you wish, please post one IN THE PROFILE.

    Email addresses in posts will be deleted for site security reasons.
    What lies behind us and what lies before us are small matters compared to what lies within us.


    Two pressures, four temperatures = SUCCESS!


    Boulder Heating Contractor


    For Consumers:

    For HVACR Professionals:


  6. #6
    Join Date
    Jun 2005
    Location
    Winston-Salem NC
    Posts
    1,133
    In NC, the homeowner is allowed to do anything, including installing their own HVAC system, gas piping or electrical systems. Only the electrical requires anything other than "Hey I live at and own the place." and even then, it is just a short test that shows you understand hot, neutral and ground.

    I have a friend in Scotland. She had a bit of a go with her heating system this past winter. From what I could gather, it was a small boiler type set-up in her attic. I told her to bite the bullet and hire a real tech on site.

  7. #7

    Talking

    Thanks Boabcelt, that was very very helpful. It has given me a very good, practical overview of the entire thing.

    Thanks very much.
    __________________________

    Darctangent -- I have recently joined an HVAC firm in NCR, India.

    I have little HVAC experience but am a mechanical engineer with a basic understanding of all aspects of HVAC. I understand HVAC drawings, heat loads, duct sizing, duct noise, chiller selection (to some extent), basics of piping/valves. I have been involved to some extent, in data collection from running HVAC plants.

    The information I am collecting is to cross check an already prepared project work, not prepared by me.

    It is an office building that requires approx 250,000 Kcal per hour of heating in the winter months in India.

    My recommendations on the above mentioned system will be used by my employer to grade me.
    Last edited by blackhawk2000; 06-20-2011 at 03:55 AM.

  8. #8
    Join Date
    Mar 2006
    Location
    Denver/Boulder
    Posts
    2,219
    Quote Originally Posted by blackhawk2000 View Post
    Thanks Boabcelt, that was very very helpful. It has given me a very good, practical overview of the entire thing.

    Thanks very much.
    __________________________

    Darctangent -- I have recently joined an HVAC firm in NCR, India.

    I have little HVAC experience but am a mechanical engineer with a basic understanding of all aspects of HVAC. I understand HVAC drawings, heat loads, duct sizing, duct noise, chiller selection (to some extent), basics of piping/valves. I have been involved to some extent, in data collection from running HVAC plants.

    The information I am collecting is to cross check an already prepared project work, not prepared by me.

    It is an office building that requires approx 250,000 Kcal per hour of heating in the winter months in India.

    My recommendations on the above mentioned system will be used by my employer to grade me.
    I see. Please understand that our rules apply none the less. after obtaining 15 or more relevant posts you would be able to request pro status and thus access the professional parts of the site.

    FYI, you should understand that water-glycol mixes have various trade offs and are due careful consideration that should be planned for during the design phase. More I cannot say. No more questions of a detailed technical nature until you can obtain pro status, please.

    See you around.
    What lies behind us and what lies before us are small matters compared to what lies within us.


    Two pressures, four temperatures = SUCCESS!


    Boulder Heating Contractor


    For Consumers:

    For HVACR Professionals:


  9. #9
    Join Date
    Jun 2011
    Location
    Glenrothes, Scotland
    Posts
    45

    Thumbs up

    Quote Originally Posted by darctangent View Post
    You will have mail shortly (if you have an Email in your profile) if not, please correct.

    correction- you have no email in your profile. If you wish, please post one IN THE PROFILE.

    Email addresses in posts will be deleted for site security reasons.
    Done

  10. #10
    Join Date
    Mar 2006
    Location
    Denver/Boulder
    Posts
    2,219
    Quote Originally Posted by Boabcelt View Post
    Done
    Good evening Boab!

    I believe you got some mail this morning
    What lies behind us and what lies before us are small matters compared to what lies within us.


    Two pressures, four temperatures = SUCCESS!


    Boulder Heating Contractor


    For Consumers:

    For HVACR Professionals:


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