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Steam to hot water heating system retrofit

Henry
Henry Member Posts: 996
We have completed two weeks ago another successfully retrofit from steam heating to hot water heating at a 25 unit luxury apartment complex. Each apartment used on average 166,000 cu ft  (4,700 cu M) of natural gas. Our projected new consumption should be near 70,000 cu ft (2000 cu M) or better. We reused the risers for both supply and return. We increase the return lines sizes in the garage and basement area so that we would have adequate flow. We used two variable speed pumps on the primary circuit due to the TRVs. We drilled and tapped the cast iron radiators for new automatic air vents. We used four KBN501 Lochinvar Knights as the heating source. We only had one return riser failure on a lower floor which was replaced.

We perform this type of retrofit about every other year. The savings in the energy bills are terrific. We usually drop the energy consumption by 1/2 to 2/3 and increase the occupants comfort.

Comments

  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    edited October 2012
    Retrofit savings

    Congratulations on avoiding some of the possible consequences of such a job. Have you kept the same boiler control system in place, or replaced it also?

    Were you maintaining the original system as well?

    One of the benefits I can see in the changeover is the much easier job of carrying of 4 relatively light boilers down instead of the massive sections of a steam boiler which must then be assembled.

    I would guess that the energy used would be the same for steam or hot water, but this install was certainly easier. Perhaps next year you can get some figures on gas consumption to post here..--NBC
  • Steamhead
    Steamhead Member Posts: 16,719
    edited October 2012
    You could get similar results

    for far less cost, and with much less risk of pipe and radiator failure, by fixing the steam system. 
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Henry
    Henry Member Posts: 996
    Steam to hot water

    The Knight boilers control themselves and with 4, it gives us a 20 to 1 micro management of the energy needs of the building. Micro management of the energy needs is one of the best ways to reduce energy consumption! The energy use of going to hot water from stema is NOT at all the same! Being able to go down to 90F in the fall or spring affords large energy savings. This is NOT possible with steam. Steam systems should only be used for production and NOT building heating or hot water aplications as they are NOT energy efficient. Please try to prove me wrong! I have done some large commercial buildings of 12 plus floors that we could not convert. I managed to reduce to reduce the energy consumption by over 35 % by reducing the pressure, replacing the boilers with Bryan water tube modulating boilers and a special DDC control panel. We converted two years ago the first skyscraper in Montreal from steam to hot water. It now consumes less than half of what it consumed before. A cathedral that we converted is down to 1/3 of what it consumed. The facts are in the figures!
  • Henry
    Henry Member Posts: 996
    Failures

    BTW, radiators rarely fail and not because they are converted. Return piping is the biggest failure in steam system converted or not! I have yet to change a steam main after nearly 40 years in the business.
  • Steamhead
    Steamhead Member Posts: 16,719
    Then you haven't seen what I've seen

    and that's not the only leak you're likely to have.



    Some time ago, I looked at a system in a church where someone converted a Webster Vapor system to hot-water- there were at least five radiators that leaked under the increased pressure. Leaked all over that beautiful old sanctuary. Then there were about five different pipe leaks.



    What happens in cases like this is you fix one set of leaks and a bunch more show up. It's like playing Whack-a-Mole, and the customer gets tired of the game real fast.



    I got out of there as fast as I could. No way was I going to touch that disaster. Wayyyy too much liability.



    Oh, and what about radiator risers that run in outside walls? If the system shuts down on a cold night, and these pipes are full of water, guess what happens? Right- they freeze. Then you have another warranty repair and possibly a damage claim.



    And if those Knights don't get regular maintenance, their efficiency will drop and they won't last as long. Guess what part of the budget property owners and managers like to cut when things go sour? Right- maintenance.



    If we can de-knucklehead a steam system and cut its fuel consumption by a third, which our company has done- and we have the numbers to back it up, which you can find in our Find a Contractor ad- there is no reason to undertake an expensive, risky conversion.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
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