tyr2005
New Member
Posts:12
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| 05 May 2008 08:40 PM |
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I am looking at a radiant floor system for a log home that I will be building. The company that I received a material quote from was recomending an Open system where a single high efficiency water heater is used to provide domestic hot water and radiant heating. This is opposed to a closed system that would use a dedicated hot water heater for radiant heating. The disadvantage of a closed system was that I would have the cost of purchaceing and operating two water heaters.
The problem that i have is that I have received different view points on these two systems. Could someone give me their experience with an Open System
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PanelCrafters
Advanced Member
Posts:680
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| 06 May 2008 07:09 AM |
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Posted By tyr2005 on 05/05/2008 8:40 PM
The problem that i have is that I have received different view points on these two systems. Could someone give me their experience with an Open System Well, #1 you or a family member could die. Ask over at Heating Help. I'm sure that you'll get some educated opinions there. |
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| ....jc<br>If you're not building with OSB SIPS(or ICF's), why are you building? |
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tyr2005
New Member
Posts:12
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| 06 May 2008 07:37 AM |
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I asked the dealer about stagnet water in the system, but being that it is open when you turn on the hot water the water flows into the house through the radiant tubing and into the heater refreshing the water. In the summer a valve can be switched so that all the domestic cold water flows through the tubing providing cooling as well as refreshing the pipes.
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jmagill
Basic Member
Posts:374
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| 06 May 2008 09:18 AM |
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We have lived with an open system for 7 years. No one has died here.
There are a few things you can do when setting up the system if you have concerns.
We plumbed it so that during the summer season( when we don't need heat), we close and open an few valves and the water run through the floor before it hits the water heater. This ensures that the whole system is flushed on a yearly basis. The other would be a installing a valve that allows you to run the water out once a year. We have this on the floor manifolds and I can just attach a hose and run the water out and down the drain.
This of course is all dependant on whether you can have an open system with regards to codes in your area and that you are willing to do the extra bit of work to keep it up. |
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NRT.Rob
Veteran Member
Posts:1741
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| 06 May 2008 09:49 AM |
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Open systems quite simply provide more risk to you, the heating system, and enter the risk of continual condensation around the pipes in summer. How much risk is hard to say. I would tend to make a one time investment to avoid all of the risks, allow for future use of glycol if needed, smaller tubing, and protect you, the system, and your house.
You can make an open system closed by adding a heat exchanger, pump, and a couple pieces of basic closed system hardware. and if your tubing is barrier pex, one of the two pumps (heating side) can be cast iron instead of bronze or stainless as it has to be in an open system, so that's a cheap "pump upgrade". If it's not barrier pex, then both pumps would need to be non ferrous (pricier).
There is no need for two water heaters just to make a system closed. |
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| Rockport Mechanical<br>RockportMechanical.com |
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warmsmeallup
Basic Member
Posts:131
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| 06 May 2008 02:11 PM |
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We were called in to install an electric radiant system OVER an open loop hydronic system when the system leaked over Christmas vacation and the homeowners came back to 3" of ice on their first floor.
What makes an open loop life threatening?...other than slipping on the ice ;) |
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| <a href="http://www.comfortradiant.com" target="_blank">COMFORT RADIANT HEATING, LLC</a><br> <a href="http://www.comfortradiant.com/zmeshinterior.php" target="_blank">Floor Warming</a><br><a href="http://www.comfortradiant.com/roof-deicing.php" target="_blank">Roof De-Icing</a><br><a href="http://www.comfortradiant.com/snow-melting.php" target="_blank">Snow Melting</a> |
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richntiff
Basic Member
Posts:108
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| 07 May 2008 11:17 AM |
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Do open systems meet plumbing code?
The risk is VERY real - it's called Legionaire's Disease. Google it along with open systems, check out HVAC help as noted above, and then decide (correctly) to NOT install an open system. |
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warmsmeallup
Basic Member
Posts:131
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| 07 May 2008 11:43 AM |
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Ok, Legionaires...how does it get there ? |
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| <a href="http://www.comfortradiant.com" target="_blank">COMFORT RADIANT HEATING, LLC</a><br> <a href="http://www.comfortradiant.com/zmeshinterior.php" target="_blank">Floor Warming</a><br><a href="http://www.comfortradiant.com/roof-deicing.php" target="_blank">Roof De-Icing</a><br><a href="http://www.comfortradiant.com/snow-melting.php" target="_blank">Snow Melting</a> |
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PanelCrafters
Advanced Member
Posts:680
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| 07 May 2008 12:47 PM |
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Posted By warmsmeallup on 05/07/2008 11:43 AM
Ok, Legionaires...how does it get there ?
From Wikipedia...
Potential sources of such contaminated water include cooling towers used in industrial cooling water systems as well as in large central air conditioning systems, evaporative coolers, hot water systems, showers, whirlpool spas, architectural fountains, room-air humidifiers, ice making machines, misting equipment, and similar disseminators that draw upon a public water supply. The disease may also be spread in a hot tub if the filtering system is defective. Freshwater ponds, creeks, and ornamental fountains are also potential sources of Legionella.
Legionella will grow in water at temperatures from 20 °C to 50 °C (68 °F to 122 °F). However, the bacteria reproduce at the greatest rate in stagnant water at temperatures of 35 °C to 46 °C (95 °F to 115 °F). |
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| ....jc<br>If you're not building with OSB SIPS(or ICF's), why are you building? |
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ReadyToRetire
Basic Member
Posts:212
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| 07 May 2008 05:16 PM |
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PanelCrafters,
Is this a theoretical risk, or are there significant numbers of recorded incidents?
Very respectfully,
Larry
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warmsmeallup
Basic Member
Posts:131
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| 07 May 2008 05:29 PM |
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Theoretical or not, if Legionaires is a risk with open loop, I have no doubt what I would do..or should I say, NOT do.
Excuse my ignorance but, you're presuming I understand how the Legionaires gets there in the first place. Doesn't "Open Loop" by definition, mean that water is not stagnant, it continues to be replaced by the supply when house water is run through faucets, tubs showers, etc..? |
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| <a href="http://www.comfortradiant.com" target="_blank">COMFORT RADIANT HEATING, LLC</a><br> <a href="http://www.comfortradiant.com/zmeshinterior.php" target="_blank">Floor Warming</a><br><a href="http://www.comfortradiant.com/roof-deicing.php" target="_blank">Roof De-Icing</a><br><a href="http://www.comfortradiant.com/snow-melting.php" target="_blank">Snow Melting</a> |
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PanelCrafters
Advanced Member
Posts:680
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| 08 May 2008 06:57 AM |
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Posted By warmsmeallup on 05/07/2008 5:29 PM
Excuse my ignorance but, you're presuming I understand how the Legionaires gets there in the first place. Doesn't "Open Loop" by definition, mean that water is not stagnant, it continues to be replaced by the supply when house water is run through faucets, tubs showers, etc..? That would really depend on how your system is designed. In some systems, the only introduction of 'fresh' water is into a storage tank. And, during the non-heating season, the water in your radiant tubing may indeed become stagnant. |
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| ....jc<br>If you're not building with OSB SIPS(or ICF's), why are you building? |
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warmsmeallup
Basic Member
Posts:131
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| 08 May 2008 08:26 AM |
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Ok, thanks PC! |
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| <a href="http://www.comfortradiant.com" target="_blank">COMFORT RADIANT HEATING, LLC</a><br> <a href="http://www.comfortradiant.com/zmeshinterior.php" target="_blank">Floor Warming</a><br><a href="http://www.comfortradiant.com/roof-deicing.php" target="_blank">Roof De-Icing</a><br><a href="http://www.comfortradiant.com/snow-melting.php" target="_blank">Snow Melting</a> |
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tyr2005
New Member
Posts:12
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| 08 May 2008 08:36 AM |
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The Open system that I am looking at has water flow through the radiant heating tube and then into the water heater not directly into the storage tank. So when I run hot water the radiant tubing gets refreshed
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NRT.Rob
Veteran Member
Posts:1741
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| 09 May 2008 12:24 PM |
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Posted By ReadyToRetire on 05/07/2008 5:16 PM
PanelCrafters,
Is this a theoretical risk, or are there significant numbers of recorded incidents?
Very respectfully,
Larry
That's a tricky question:
http://www.cnn.com/HEALTH/library/DS/00853.html
legionnaire's disease is very difficult to diagnose as it resembles the flue very strongly.
In fact, some portion of flu deaths are very likely legionnaire's disease.
it's not theoretical. it's also not likely you'll get it. not likely of course, doesn't mean you won't either.
thing is, a one time expenditure to make a system closed eliminates all and any risk to you, as well as risks to your system's lifespan and efficiency.
And if you then choose not to use otherwise unnecessarily huge pipes required by open systems that allow all incoming fresh water to pass through without ridiculous pressure drops, then you'll probably save the amount of money the heat exchanger would cost you right there. and get a better system to boot.
In short, open systems don't have any real good points. If you do it cheap (small pipe, not flushed regularly), you aren't doing it right. If you do it expensive (big pipe), you aren't saving much money and your system won't be as good because your pipe spacing is likely to be wide.
and the condensation issue still remains. There is a reason we are not all just pumping cool water into our radiant systems and calling it a cooling system. |
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| Rockport Mechanical<br>RockportMechanical.com |
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ReadyToRetire
Basic Member
Posts:212
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| 10 May 2008 09:55 AM |
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NRT.Rob,
Thanks for your clear reply.
Very respectfully,
Larry
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dmaceld
Veteran Member
Posts:1465
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| 10 May 2008 05:33 PM |
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If your local jurisdiction has adopted the International Residential Code for plumbing, forget the open system. It's not allowed. Here's the quote from the 2006 IRC, Chapter 28.
"Water heaters that will be used to supply potable water shall not be connected to a heating system or components previously used with nonpotable-water heating appliances."
Apparently the Uniform Plumbing Code does allow it. I came across a Texas Gas document where they are offering incentives for folks to install a combo water heater, one burner heats both potable and space heating water.
There's also an issue of temperatures. The potable hot water heater should be 140F min for safety but your radiant heating system may need to be lower.
I'd say there's enough questions and issues with an open system that you'd be better off with separate heaters. Besides, water heaters aren't that terribly expensive.
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| Even a retired engineer can build a house successfully w/ GBT help! |
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whitealan
New Member
Posts:11
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| 11 May 2008 04:01 AM |
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If you are going to build a log home, please make sure you build it with a “good envelope”, that will be money well spent. Log houses are notorious for the impossibility to build them as a reasonable well sealed house. Wood (logs) is about 90% efficient to let heat and moisture to go through the wood itself let alone where the logs join. Be prepared to expend more energy to heat (or to cool if you have a cooling season) no matter what. If you build a radiant floor heating with plex you’ll have temperature banding and you will also need higher water temperature and it will cost you more $$ energy of course. Besides, plex tubing (8” or more on center) will produce microscopy dust lifting and that will be bad if you have any dweller that has any pulmonary problem (asthma?) and it won’t be very healthy in the long run to those who currently have no pulmonary problems.
If you still decide to go a log home for the beauty of it and you want radiant heating, install it just below the wooden floor, then use capillary tubes that are 3/8” on center and will avoid the banding and the dust lifting due to much, much reduced air plumes from the banding itself. You will run less water not only slower and void pipe noise but also at lower temperature that will save you $$$ energy. You can visit www.bekausa.com to get acquainted with this close system for radiant heating and radiant cooling.
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BadgerBoilerMN
Veteran Member
Posts:2010
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| 04 Jun 2008 11:00 AM |
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Open systems are not accepted practice -with exception of hyrocoils- your vender risks your health in order to make the system DIY friendly.
You may use a plate heat exchanger or a water heater with a built-in coil such a Combi-cor without worries. DIY'rs should be extra careful to follow accepted practice as they generally lack the education and always lack the experience when designing extraordinary systems. |
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| MA<br>www.badgerboilerservice.com |
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