retrogreen
New Member
Posts:2
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| 20 Jul 2008 04:06 PM |
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As a consumer, not an HVAC specialist, I need advice !
Can we utilize geothermal technology with our existing steam radiator system ? We have a commercial building of about 5800 square feet of heated space. |
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Palace Geothermal
Veteran Member
Posts:1609
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| 20 Jul 2008 04:19 PM |
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Hi, Welcome to the forums. Sorry but geothermal will not work with steam radiators. The hottest water you can realistically get from a geothermal unit is around 120°. |
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Dewayne Dean
<br>www.PalaceGeothermal.com<br>Why settle for 90% when you can have 400%<br>We heat and cool with dirt!<br>visit- http://welserver.com/WEL0114/- to see my system |
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retrogreen
New Member
Posts:2
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| 20 Jul 2008 04:32 PM |
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Thanks geodean ! Bummer ! So the optimum is air ? That radically increases the cost of the project !!! Major new ducting in a 19th century building...
specifically though, as a DIY carpenter, is the duct size for geo the same as for oil fired hot air ? And, would I need the same ratio of registers per square foot as for ofha ? |
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Palace Geothermal
Veteran Member
Posts:1609
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| 20 Jul 2008 05:28 PM |
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Ducting for geo needs to be bigger since the air is not as hot. You can do a hot water geosystem and then have hydronic air handlers. |
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Dewayne Dean
<br>www.PalaceGeothermal.com<br>Why settle for 90% when you can have 400%<br>We heat and cool with dirt!<br>visit- http://welserver.com/WEL0114/- to see my system |
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joe.ami
Veteran Member
Posts:4377
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| 21 Jul 2008 09:13 AM |
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R.G.
Get some bids from the local guys. Many of us are glad to install a system in your duct work and would be happy to size it for you as part of the job. Or if you care to do everything yourself, pay a contractor to design the duct work for you. A few hours wages will be well worth the investment to have the results warrantied by a pro.
Good luck. |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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Bill Neukranz
Veteran Member
Posts:1103
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| 21 Jul 2008 09:23 AM |
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Posted By geodean on 07/20/2008 5:28 PM
Ducting for geo needs to be bigger since the air is not as hot ... I'm curious to understand more technical detail that supports this comment. Many thanks. Bill |
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Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
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joe.ami
Veteran Member
Posts:4377
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| 21 Jul 2008 09:46 AM |
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It's not a "technical" kind of thing. The hotter the air the greater effect you can have on the space you are conditioning. With a fossil furnace, even poorly design ducts might get the job done. As geo is a refrigeration process, air flow is much more important, poorly sized duct will not get the job done. The International Mechanical Code calls for additional return air on heat pumps as well.
It's common knowledge; but if you like, the "technical details" are available in Manual D for you.
Joe |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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Bill Neukranz
Veteran Member
Posts:1103
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| 21 Jul 2008 10:27 AM |
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Posted By joe.ami on 07/21/2008 9:46 AM
It's not a "technical" kind of thing. The hotter the air the greater effect you can have on the space you are conditioning. With a fossil furnace, even poorly design ducts might get the job done. As geo is a refrigeration process, air flow is much more important, poorly sized duct will not get the job done. The International Mechanical Code calls for additional return air on heat pumps as well.
It's common knowledge; but if you like, the "technical details" are available in Manual D for you.
Joe Hmmmm... I can appreciate the need for properly sized ducts to ensure efficiency and comfort, regardless of heating/cooling source. That's a different statement than the design statment: "ducting for geo needs to be bigger since the air is not as hot." And I can appreciate that if the duct work is not designed properly that perhaps a fossil fueled heat source might be more forgiving - but that doesn't include the cooling side. Thanks for helping that it's common knowledge - I just hadn't heard this before (duct sizes need to be larger for geo). I have pretty good familiarity with Man D. I looked through my book again this morning to find the details. Unfortunately I couldn't find it. Perhaps you could kindly point me to the information in Man D. Many thanks. Bill |
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Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
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tuffluckdriller
Advanced Member
Posts:630
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| 21 Jul 2008 10:35 AM |
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Generally speaking, ducting for geo needs to be bigger because of the cfm design calculation.
CFM=BTUhs/(1.08 x delta T)
With this formula, you should note that a lower delta T will require higher CFM. With geo only putting out 90-100 deg. F. air, you'll see a higher cfm required to heat the home. With a fossil fuel furnace, you'd see a higher delta T, and therefore, less cfm required. Less cfm means smaller duct.
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| Clark Timothy ([email protected])<br>Geothermal Heat Pumps: Heating and Cooling that's Dirt Cheap!<br>www.pinksgeothermal.com |
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cnygeo
Basic Member
Posts:170
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| 21 Jul 2008 10:36 AM |
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Edit - Clark beat me to it and explained it better! |
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cnygeo
Basic Member
Posts:170
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| 21 Jul 2008 10:49 AM |
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If the steam radiators are grossly oversized (by a factor of 4 or 5 at least) and if they are of the correct sort they could possibly be converted to a low temperature hydronic system that could be run by a heat pump. This is highly unlikely, though, and even if theoreticaly possible there are a whole host of practical issues such as flushing out all the rust from a 100 year old system, whether the system would handle the water pressure without developing a host of leaks, etc. So I really should have saved myself some typing and just said "no".
There are other options for retrofitting geo other than adding ducts, though, assuming you don't care about the cooling. Radiant ceiling and/or wall panels can be relatively easy to retrofit. New steel panel radiators can be installed if you have the space available (they will be large to work at the low temps). Individual fan coils can be installed in each room so that you only have to snake PEX through the walls instead of big ducts. Once you've had steam heat (assuming the system is well set up) you might not like forced air, unless it is a really well designed system.
Without knowing anything about your building it is impossible to say which option would be best. In my house radiant ceiling was the option with the lowest cost and least tear-up. If preserving the appearance of the building is at all important, radiant ceiling won't alter the look of anything unless your ceilings are decorated somehow. |
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Bill Neukranz
Veteran Member
Posts:1103
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| 21 Jul 2008 12:07 PM |
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Posted By tuffluckdriller on 07/21/2008 10:35 AM
Generally speaking, ducting for geo needs to be bigger because of the cfm design calculation.
CFM=BTUhs/(1.08 x delta T)
With this formula, you should note that a lower delta T will require higher CFM. With geo only putting out 90-100 deg. F. air, you'll see a higher cfm required to heat the home. With a fossil fuel furnace, you'd see a higher delta T, and therefore, less cfm required. Less cfm means smaller duct.
Thank you! (page 3-7, Man D) Best regards, Bill |
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Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
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