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Need help rating these radiators.

GPGP Member Posts: 25
Hello to all.  First of all Thank you to Dan Holohan for the EDR book. 

It's amazing.  I'm a property manager of a church in Chicago and I'm

trying to determine the ratings of our radiators in our sanctuary. 

We are going to replace the steam boiler with a geothermal heating AND Cooling

system.  I've been told by one contractor we need 40 tons, 50 by

another, and 30 by even another.  So I bought the book EDR and it's

perfect.  I'm going to determine the actual heating capacity that we

have now and compare it with the quotes.

SO, for all the radiators (this is a 2 pipe steam system), I can easily calculate the total square foot

of radiation.  BUT there are 8 radiators that are fin type radiators. 

They are in an enclosure, (similar to a national cabinet enclosure lets

say).  However, in my case, there are also blowers on the radiators. 

Basically squirrel cage fans to blow air over the fin type radiator to

transfer heat more quickly.  

My question:  Is there a way to calculate how much BTUs I'm getting from

these?  Can I calculate my CFMs on the blowers and use this somehow in a


Please advise!  Any help is much appreciated. 

Thanks again,



  • SWEISWEI Member Posts: 7,356
    edited June 2014
    The ratings depend on temperature

    Unless there have been some envelope upgrades, it's quite likely you will not be able to heat the building on a design day with a heat pump and the existing radiation. has a lot of useful info.  Note in particular the derating of EDR for temperature on p. 37 and remember that the vast majority of heat pumps can't supply water hotter than about 130ºF.
  • GPGP Member Posts: 25
    edited June 2014

    Thanks for the response.  I should clarify, We are going to rip out the existing boiler, piping, radiators, etc.  and then install a brand new geothermal system.   The new geothermal system would provide cooling and heating.  We've had three different contractors tell us three different numbers:  One said 50 Tons, the other said 40, and even another said 30 tons of cooling is what we need.

    What I'd like to do is calculate the current total value of radiators already present in the sanctuary.  E.g. if for example there is the equivalent of 40 "tons of heating", then I know we probably won't need 40 tons of cooling.  The 30 ton quote might be closer to the actual needs. We're a church located in Chicago.  80 year old building, with lots of stained glass, 53 foot ceilings.

    BUT MY REAL QUESTION IS THIS We have 8 radiators that are fin type radiators.  They are in an enclosure, (similar to a National Cabinet enclosure lets say).  However, in my case, there are also blowers on the radiators.  Basically squirrel cage fans to blow air over the fin type radiator to transfer heat more quickly.   My question:  Is there a way to calculate how much BTUs I'm getting from these?  Can I calculate my CFMs on the blowers and use this somehow in a formula?
  • JStarJStar Member Posts: 2,668

    Why not keep the steam and add A/C separately?
    - Joe Starosielec
  • GPGP Member Posts: 25
    edited June 2014
    Keep steam and add A/C separately

    What I understand, when a Geothermal system is installed, the wells work for cooling and heating.  The only thing you would need is a heat pump that can work in cooling mode and heating mode which is pretty standard.  The system would have what's called a reversable  valve which allows the heat pump to switch from heating/cooling mode.  So you're paying for an AC system and getting heating - a very efficient heating system - for virtually no cost.

    So the question that should be asked is "Why NOT get a new heating system?"
  • SWEISWEI Member Posts: 7,356
    Who's designing the geothermal system?

    there is sophisticated software for this, sometimes even free from the manufacturers.  Sizing of coils is critical and depends on heat loss/gain as well as latent (dehumidification) loads.
  • I'm in Chicago

    A full geothermal system for heat really does not make financial sense.  You will end up putting in a system probably three times bigger than if you left the steam heating in and used the geothermal in more moderate weather which occurs for 90% of the heating season. Or in other words, you will end up putting  in a system 3 times larger so it can heat the building for an additional 5 to 10 days a year.  In addition, churches usually set temperatures back deeply and need large amounts of heat to recover, making it very difficult for a geothermal system to be cost effective.

    The other problem I usually find is grossly oversized cooling equipment.  If you are looking to keep a typical high mass building sanctuary at reasonable comfort you only need about 3 to 4 tons per 100 people.  If you want full cooling, maybe double that.

    Also, if you are using the geothermal for forced air, you will have about a 20 to 30% higher heating need than if you used an efficient system such as steam or hot water ( just check out the DOE testing)  There is a reason why most of the world does not used forced air for heating and what little is left outside the US for cooling is disappearing from use as more efficient systems are installed.

    If you have an existing steam system, and spend some money getting it working properly, you will have about the most efficient heating system available, especially for two pipe steam.  

    If you are interested, I am currently scheduling some seminars in the Beverly and Rogers Park or Edgewater areas  ( and maybe in the Bronzeville areas )particularly addressing churches with steam heating on how to upgrade, restore and maintain these incredible systems.  

    I already have a standard seminar scheduled at the Rebuilding Exchanger and will be teaching at the Chicago Center for Green Technology again this fall.
    The Steam Whisperer (Formerly Boilerpro)

    Chicago's Steam Heating Expert

    Noisy Radiators are a Cry for Help
  • SWEISWEI Member Posts: 7,356
    edited June 2014
    You're in luck!

    Dave works in your area and will not steer you wrong.

    For an intermittently-occupied minimally insulated building (like a sanctuary) nothing can touch steam for quick recovery.  You really can have the best of all worlds with a properly designed (and controlled) hybrid system.

    Properly implemented geo-exchange is a beautiful thing, but modern inverter-driven air source heat pumps often represent a better bargain (unless you happen have a large body of water or free-flowing stream on site.)
  • nicholas bonham-carternicholas bonham-carter Member Posts: 6,535
    Keep the steam, and make it work as it did when new

    You will be in good hands with Dave who is a regular contributor here. If you do a search for him, and read his postings, you will have the measure of the man himself.

    Download the heat-loss program from SlantFin , and figure out your heat-loss.

    As SWEI has said,, Steam has the advantage of having a quick recovery of temperature before the congregants arrive, and uses very little electricity unlike hot water.--NBC
  • Jamie HallJamie Hall Member Posts: 6,653
    Two comments...

    First, as several folks have said, save yourself and your church a whole pile of money and get Dave over to refurbish the steam system for your heating needs.  Then add just enough air conditioning capacity to keep folks happy in the summertime.

    Second, though, if your congregation is bent on appearing greeny (they won't be; refurbishing the steam system is actually a lot greener) and ripping out the whole existing system and getting the geothermal, you need to have someone -- might be one of the contractors, but better would be a well-qualified HVAC engineer to determine the actual required heating and cooling loads, including allowances for capacity for rapid recovery for services.  Granted, the existing system may give you a sort of a ball park figure, but that's not adequate for what you need at this point.

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • GPGP Member Posts: 25
    Fin tube radiator with blower

    Guys, thanks for the responses, but nobody seems to know how to help me.

    I'm trying to find out how to measure the heat output of a fin type radiator with blower.  Does anyone know how to do this?  I have Dan's book and can calculate this with the radiator ONLY but now with a blower on it. 
  • SteamheadSteamhead Member Posts: 11,328
    Two points:

    1- Radiators with blowers- also known as fan-driven convectors- were never standardized like a lot of cast-iron radiators were. We would need to know who made these units and what their dimensions are. Pictures would help.

    2- Calculating the heat loss of a building is not, has never been and will never be the way to determine an A/C load. They are two entirely different things.

    You've had recommendations to contact Dave Bunnell, "The Steam Whisperer", and I'll add my recommendation. He's one of the best in the business. Why don't you get in touch with him?
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • GPGP Member Posts: 25
    edited June 2014
    Geo vs. Steam

    Our gas bills last year were over $20,000.  And this is just maintaining the building at 50 to 55 degrees 90 to 95% of the week in the winter.  The other 5 to 10% of the week, we adjusted the temp to 68 - 70 degrees.   We've calculated that by installing a this geothermal system, we'd save close to $9,000 to $11,000 in gas bills. 

    Gas prices are forecasted to increase considerably over the next 6 years.

    So, as I mentioned, we really started out looking at a conventional rooftop AC system, but quickly learned that we could have a new heating system too. 

    All the conventional roof top unit bids came in at $400 to $450K, including the necessary structural steel needed to support the rooftop unit.

    On the the other hand, all the geothermal bids have come in at $400K or less. 

    One guy has bid for a ductless system.  The airhandlers would sit right in the sanctuary.  The 4 heatpumps would be the basement.

    I visited a church in Oak Park (15 miles west of Chicago) which had a 50 ton geothermal system installed 3 years ago.  Their building is similar to ours.  (On the other hand, they are using airhandlers with lots of duct work.)  In any case, they kept their old steam system JUST to be safe but they haven't needed it.  Even during this past brutal winter, their geothermal system held up fine. They have saved on average over 10K per year in gas bills. 
  • ChrisJChrisJ Member Posts: 8,597

    Call Dave,

    If you don't you're making a big mistake. 
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

    Steam system pictures
    Central air project pictures
  • JStarJStar Member Posts: 2,668

    1. Upgrade the steam system

    2. Save 30-50% on the fuel bill

    3. Put that $400K towards something useful like feeding the hungry, or building shelter for the homeless.
    - Joe Starosielec
  • SWEISWEI Member Posts: 7,356
    For this size and complexity of project

    You really do need some professional expertise.  The sizing of A/C versus heating loads is one area, as mentioned above.  Occupancy patterns make a significant impact.  If the sanctuary is used once per week, mostly uninsulated, and constitutes the bulk of the total facility load (quite common in older churches) that skews things significantly, and in a manner which standard equipment sizing programs will not account for.  Air distribution in high-ceiling rooms is in itself an art form, and one which the Asian split makers have not generally addressed.  There are ways to do it (by pairing their short-duct evaporators with special nozzles) but it's not common knowledge amongst the installer base.

    We are trying to help you be careful with your congregants' money.
  • SWEISWEI Member Posts: 7,356
    Energy Costs

    Every year, a larger portion of our domestic electricity is produced from natural gas.  When the power company burns gas, it only converts 50-60% of the available BTUs into electricity.  An additional 20-25% is lost in distribution.  Net net is that you are lucky to see 40% of the BTUs that are burned delivered to your premises.

    A properly functioning commercial steam boiler will convert about 85% of those BTUs into heat.

    Don't be lulled into complacency by the power company PR.
  • SteamheadSteamhead Member Posts: 11,328
    If you click on my company's name

    at the bottom of this post, it will take you to a discussion of a project where we cut a co-op building's gas consumption by a third- by de-knuckleheading the steam system. Despite what you may have been told, it really is possible.
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • nicholas bonham-carternicholas bonham-carter Member Posts: 6,535
    An interesting point

    Good point to make SWEI, that heating with electricity is less Green (and more expensive) than heating with gas, in terms of carbon footprint.

    Let's have some pictures of the fan-coil unite, and of the boiler, and maybe we can get your heating bills reduced with a few relatively simple alterations.

    The desire for fuel economy is nothing new, and when your church was first built, steam was chosen for its economy, and comfort. Over the years, various repairs, and modifications, made by well-meaning, but unqualified people have made the system perform poorly, struggling to do its job, and burning extra fuel as a result.

    What handles the air conditioning now?--NBC
  • GPGP Member Posts: 25
    3 things...

    I need to do...

    1.  Get pics of the fin radiator and fans up here.

    2.  Take some time and re-think this entire project with the property committee (as you guys are suggesting).

    3.  Last but not least, get in touch with Dave!
  • GPGP Member Posts: 25
    Pics of the radiators

    Guys, thanks again for your are some pics.

    I hope these are viewable.  So there are two rows of fin tubes.  Each fin tube is about 6 inches square and about 40 inches long.  They really do work well.  With the fans running they pump out a lot of heat.

    I'm guessing, as one of you mentioned, these aren't too standard.  I can't see any manufacture's labels anyhow.

    The squirrel cage blowers are about 400 CFMS.  So I figure about 800 CFMs to 1,000 CFMs total.   I'm wondering if I use Dans book, I can just estimate the EDR from the fin tubes, and then guesstimate an additional 40% increase in heat output due to the blowers?  Any thoughts on this approach? is 30% a better guess???
  • GPGP Member Posts: 25
    geo vs steam

    I realize I got two topics going on in one thread...I'm going to post another thread and talk about some of the good points you all have made.  See "the wall" for this.
  • GPGP Member Posts: 25
    edited June 2014
    Thanks for the referral

    Guys, I took your advice and contacted Dave.  Met with him a few days ago, walked through our buildings, and learned A LOT from  him in a couple hours on sizing equipment, efficiency of steam, using hybrid systems.  He also pointed out some serious problems with my current set up as in bad installation, poor decisions on installer's part (e.g. 1 of many, removing the vacuum/condensate pump).   I only wish I knew of Dave 10 years ago when we had these new boilers put in.

    Anyhow, the short of it is, I fired my current boiler guy, and have hired Dave to do some steam work to "summer-ize" my systems, clean the boilers, McDonald Millers, burner, and give advice on how to get them in order. 

    The long version is I'm going to push our committee to take a step back and rethink the entire geothermal system.  See next post in "AC, heat pumps and Refrigeration" on sizing equipment, calculating cooling.  Please visit that post and give me some advice there!

    Thanks to all of you and Dave.
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