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  1. #1
    Join Date
    Aug 2006
    Location
    Ballwin, MO
    Posts
    49

    Advice on Bids for Church

    Hi,

    I have bids from four HVAC contractors to replace the 40-year old HVAC systems in a church. I have received estimates for cooling that vary from 7 tons to 10 tons.

    For reference, we currently 7 tons of cooling, but performance is abysmal because there is no air flow. That's attributed to there being no return ducts. And, I mean no return ducts. Just a whole for the air to go into. For cooling, hot air from the upper level has to migrate down the stairs to the basement.

    I haven't done the calculations myself and the answers from the estimators vary as you can see up to 30%.
    Bid #1 - 8-ton (padded to 9-ton) bid estimator said he hired an engineer to do the estimate.
    Bid #2 - 10-ton bid estimator was meticulous. Measured every window, every part of the building. From very big company with commercial and residential divisions.
    Bid #3 Another 8-ton bid. Said it would take an additional 6 tons for fresh air blend.
    Bid #4 The 7-ton bid is from a company I have used before and thought their work was top-notch. This bid is $5,000 less than the others. This is attractive unless he got the tonnage wrong. I swear he said his bid included fresh air blend.

    Thanks for insights you have,

    Dan

  2. #2
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,350
    you are in a tough spot...and churches/schools are the worst to bid because...

    1. they typically have very little money (that is the sad part)
    2. the heating and cooling loads are extremely variable

    for you, the low, 7 ton bid, is probably pretty accurate for a constant load. the 10 ton bid is probably pretty accurate considering that your load (people) will show up quickly (giving you a high cooling need) and then leave quickly (no-load to full-load to no-load in 1 hour is 'quickly' to a heating and cooling technician). churches typically wait until the last minute to turn any equipment on to save money as well (see #1 above). this creates an even greater load since we now have a building to cool down (in addition to the people load).

    the fact that you brought up the duct work (or lack of it) tells me that perhaps you should fix this first. if i installed 1000 tons of cooling in your church, but you can't let me move enough air to use it, then it was a waste of money. you might find out that your current equipment is large enough and ok after all.
    "Mother" is the name for God on the lips and hearts of children....The Crow

  3. #3
    Join Date
    Aug 2006
    Location
    Ballwin, MO
    Posts
    49
    jayguy,

    Thanks for your patient response. So, fixing just the ductwork is a great idea that we'll consider, but I think it's not viable. The equipment range from about 30 to 40 years old and has not been reliable. We just put $3,000 into try to keep it running. People thought we were good for another year. I warned them it wasn't. And, then a package unit pumped out all its R-22. (0 pounds on the low and high side.)

    I think your analysis of load is helpful. Having a building sit there unused and then all the sudden have it full of 90 people with lots of lights is important. People and lighting could add over 40,000 BTU of heat gain.

    Thanks,

    Dan

  4. #4
    Join Date
    Jun 2010
    Location
    Philadelphia PA
    Posts
    2,190

    It's not what you have ,,,it's how you use it

    I suspect if the fresh air per person was considered, you would need 5 tons of air just to temper the fresh air as per commercial design. Is that really necessary for a space (usually large cube) that has people for a short period of time? NO I don't think the CO2 levels will change but it is a rule.
    If it gets really hot are you going to turn it on at 6AM and expect the church to be comfy at 9AM? Common sense (if there is such a thing ) would suggest otherwise SO if you get the Church pre cooled the night before then any of these technically deficient sizes should get you what you need, at or less than 80 degrees with some lower RH and the stuff inside the church also pre cooled to provide the thermal mass to healp things along.
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  5. #5
    Join Date
    Aug 2006
    Location
    Ballwin, MO
    Posts
    49
    genduct - thanks. I understand that there are a lot of variables and that pre-cooling the building can help.

    I have a question that I would like some help with. Given that the church will be used several times a week, but not continuously like a commercial building usually is, what efficiency furnace and what SEER A/C makes the most sense? Perhaps another way to put the question is, what efficiency would pay for itself in 5 years?

    The Sunday School is in a basement that is 25' x 55', what size furnace would suffice. All the bids have package units. But, one bid included a 105,000 BTU furnace and that seemed like too much for a basement in St. Louis. There's a lot of thermal mass, so maybe that much BTU is needed to warm up.

    Thank you,

    Dan

  6. #6
    Join Date
    Jun 2010
    Location
    Philadelphia PA
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    2,190

    A l;ittle topugh when you can't see what you're talking about

    But in general, the 105,000 BTU might be a good (oversized choice) if you let the temp drop when no one is there and you need to recover quickly so the extra capacity is no longer extra but needed. Especially with the thermal mass you spoke about

    As far a efficiency is concerned there is operating cost and owning cost. seems that everyone is focused on the high SEER and not looking at the cost of an ECM motor vs. a PSC motor for instance. All that complexity that gives you that efficiency is also very expensive to repair and replace when it breaks.

    My opinion is the min efficiency or just a level above vs going to the moon with the latest greatest. You also need to vote with your pocket book so you probably will have the decision made for you.

    Use my contact info if you would like to talk off line
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  7. #7
    Join Date
    Aug 2006
    Location
    Ballwin, MO
    Posts
    49
    Everything you are saying seems like common sense. Thanks.

    The contractor I have previous experience with called me out of the blue today. That was good.

    genduct, did you mean call your ph #, or did you want to talk offline another way? (I didn't see any other contact info.)

  8. #8
    Join Date
    Aug 2009
    Location
    Jurupa Valley, CA
    Posts
    1,777
    Precooling is the biggest problem i've noticed in churches (meaning, they never do it). There's no excuse these days, with $40 thermostats that can be programmed 7-days, to NOT pre-cool the building before scheduled services. The patchwork solution always seems to be put in massive units that end up working hard in the hottest parts of the day (when they are least efficient). In the summer, I'd wager you'd save MORE money running at a COLD set-point overnight sat-night to get the place down to 68F, then have it set at whatever is comfortable for morning/afternoon services. (the 'cold' 68 would rapidly come up to comfortable levels once the crowds arrive, but the building being cold will help out the equipment in the heat of the day.

  9. #9
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    Quote Originally Posted by CraziFuzzy View Post
    Precooling is the biggest problem i've noticed in churches (meaning, they never do it). [COLOR="Red"]So do it.[/COLOR].
    Ventilation: Code requires 15 cubic feet per minute of ventilation air for every occupang. If there are 80 people that is 1200 cfm. The 8 ton system is supposed to move 3200 cfm. That means that whenever the machine is running 37.5% of the air will be outside air at that is considerably warmer than the thermostat setting inside.

    Most systems have fixed outside air for ventilation. This ventilation air is not needed when the building is unoccupied and less may be needed on other occasions. The ventilation air can be controlled by a CO2 monitor that senses the carbon dioxide of occupants and opens only as needed for ventilation. This is a smart investment.

    Other: Minimum SEER equipment is your best choice with CO2 controlled ventilation air. I also recommend at least 2 stages of cooling and heating. Also it sounded, in Post #1, as if the ducting is a problem. Fix your duct leakage and airflow problems as your first priority.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  10. #10
    Join Date
    Jun 2010
    Location
    Philadelphia PA
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    dancarne

    Feel free to call my C # The conversation could be simplier
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

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