nick_083
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| 03/07/2009 11:05 AM |
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I've been reading posts here, about how bad the open loop systems are. The main reasons seems to be the growth of Legionella.
After reading several professional articles on Legionella, such as this one: http://www.legionella.org/faq_professional.htm#a7 the conclusion I reached is that you need to maintain the water temperature temperature greater than 60C (140F) in your hot water tank and also in the hot water distribution system. Frankly speaking I cannot think of too many people, who are running they water heaters that hot - and even if it is that hot.... the recommendation is to install the mixing valve, which is effectively going to keep the temperature colder at least in the system. I would imagine the vast majority of the households in the US are keeping their temperature at 120F level, however there doesn't seem to be a growing awareness among the population about keeping the hot water systems steaming hot... or installing UV or copper-silver water treating systems.
Now the real question: how is installation of open-loop system different then just 120F water heater (factory preset settings) with no radiant floor at all? I would imagine they create an almost equal risk of Legionella contamination.
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BadgerBoilerMN
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| 03/07/2009 11:18 AM |
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The more immediate reason is the low efficiency, high maintenance and reliability issues.
Water heaters are not designed to heat space. We call such appliances boilers. The standards are different and they cost more for that reason. The proponents of such systems (those who sell them and those who want something for nothing) are looking for a cheap shortcut and often suffer for their shortsighted opinions.
Very popular with the DIY crowd for price and apparent simplicity.
Professionals (and mechanical/plumbing codes) shun such systems for good reason.
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MA
www.badgerboilerservice.com |
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NRT.Rob
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| 03/07/2009 11:22 AM |
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Radiant floor offers a heck of a lot more surface area (inside of the pipes), while only marginally increasing water volume. That increases the concentration of the "baddies" possible in the water significantly, and it is concentration that is a problem; we all fight off legionella every day in low concentrations.
We do recommend 140 in the water heater with a tempering valve, but lately point-of-use anti-scald valves allow the 140 to run out to the fixture without hurting the occupants.
There are lots of other reasons not to open loop anyway, legionella is just one. |
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-=Northeast Radiant Technology=-
NRTradiant.com |
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Blueridge company
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Posts:211
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| 03/07/2009 12:20 PM |
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If you must heat of a water heater think about this option, I have mentioned this before we sell it as do others, TACO X BLOCK. for about $950.00 you are strapping on to your water heater a pair of bronze pumps and flat plat heat exchanger good for about 50,000 BTU, temperature modulation, and a host of other features . You can keep your domestic at 125 year round and your in floor at 110 or what ever. no reason to go open loop. Open loop is just problems waiting.
Dan |
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Dan
BlueRidgeCompany.com |
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ICFconstruction
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Posts:638
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| 03/07/2009 9:59 PM |
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| Isn't an on demand tankless water heater the way to go for radiant heat? |
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Brad Kvanbek - ICFconstruction.net |
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nick_083
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Posts:6
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| 03/07/2009 11:05 PM |
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| What do you guys think about these Bradford White models with dedicated heat exchangers? They seem to support closed loop applications. http://www.bradfordwhite.com/products_list_grc.asp?id=13 |
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BadgerBoilerMN
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| 03/08/2009 10:52 AM |
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I like the Combi 1 very much and use it often for basements, additions and smaller homes.
Tankless water heaters make very poor space heaters. They are water heaters!
I use more conventional water heaters than tankless, which more closely resemble convential boilers in operation and replicate their more forgiving nature.
Careful system design is more important when using any alternative heat source. |
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MA
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tesla-was-right
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| 03/08/2009 4:39 PM |
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| If anyone would like a simple, cost effective, proven additive to kill legionella , such is available |
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BadgerBoilerMN
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| 03/09/2009 5:44 AM |
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"Additives" ?
The answer was Don't use open system designs. The vast majority of residential hydronic systems do not need additives of any kind. Exceptions to this fact should be determined by a professional. |
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MA
www.badgerboilerservice.com |
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RichColorado
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| 03/09/2009 9:23 AM |
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| Could someone define "open loop" and "closed loop" systems? I thought I knew, but this thread has me confused! |
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jmagill
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| 03/09/2009 10:20 AM |
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Posted By RichColorado on 03/09/2009 9:23 AM
Could someone define "open loop" and "closed loop" systems? I thought I knew, but this thread has me confused!
Closed loop means no radiant heating water mingles with domestic water.
Open will |
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CeeElGeeDIY
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| 03/10/2009 1:04 PM |
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Hopefully I won't hijack this thread but after doing a bit of research it seems that most of the folks who could answer my question are already here. So ...
My wife solicited a quote for a radiant system from a national brand (Radiantec), something that appeals to her because of its DIY nature and cost. They came back to us with an "open direct" system that runs all hot water, domestic or otherwise, through the radiant floor-heating system. This is not a small system, intended to heat our 2,200 sq. ft. ICF home. They have a $3,500 Polaris HWH doing all the work for both radiant and DHW. He claims this system does meet all codes and would even have my wife believe that the water circulating through the floor in the summertime is a cooling benefit. After reading what many have already said about open systems, I raised objections. The Radiantec rep wants to know why. What do I tell him?
By the way, we do have a local contractor coming in with his bid for a closed system that will use a mod/con boiler. She's expecting it to be a lot more expensive than the Radiantec! |
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RichColorado
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| 03/10/2009 1:10 PM |
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Posted By jmagill on 03/09/2009 10:20 AM
Posted By RichColorado on 03/09/2009 9:23 AM
Could someone define "open loop" and "closed loop" systems? I thought I knew, but this thread has me confused! Closed loop means no radiant heating water mingles with domestic water. Open will
That is what I thought, but the "additives" in the open loop suggestion had me doubting what I already knew.
Thanks! |
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NRT.Rob
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| 03/10/2009 1:23 PM |
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1. What about floor condensation when cold water runs through it? Can it be guaranteed that is not a problem? How?
2. Why not protect the system from whatever is in your water, and you from your heating system pipes' avaiable biofilm area?
3. Why not buy a mod/con and indirect for a bit more and get even more efficiency? Or, what is your actual heat load, and is either the polaris or a mod/con actually cost effective?
4. What if you, or a future owner, ever need to antifreeze the system for any reason?
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-=Northeast Radiant Technology=-
NRTradiant.com |
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jmagill
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| 03/10/2009 2:00 PM |
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I am going to reply. Please know that I am not a proffessional just a home owner.
1. A plumber would not spec and install an open system as it is possible liability issue.
2. I installed and live with an open system in a small home. It was a viable cost effective system and I take full responsbillity for it's upkeep. I don't call a plumber when I have problems I do it myself.
3. I have it set up so I can switch between open and closed if ever need be.
4. I have it set up so that I can run cold water through it in the summer. No problem with condesation but it does not really make enough of a temp difference to be of any use other than preheating water. I do however use it to make sure that no water is stagnant through the non heating season.
My conclusion is.
It is great for a small house with a simple system that you will maintain yourself.
It would be more cost effective to buy one of the combiboilers etc that seperate the systems if you have a larger home that is more complex.
If you are going to not maintain your own system or sell anywhere in the near future go the safe route and have a closed system. |
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jmagill
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| 03/10/2009 2:15 PM |
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I can give you one good example of why not to do an open system.
If the water goes off and you get an air bubble in the system, will you know how to bleed it out of your radiant system?
If you will not be able to do this then don't install an open system.
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BadgerBoilerMN
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| 03/10/2009 2:21 PM |
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I sure the next owner of your home will take the same careful, thoughtful care of your system and be equally aware of the risks involved.
Thus codes and licensed plumbers like myself.
There are too many reasonable and completely safe alternatives to open systems to take unnecessary chances.
I seemed to get by without wearing seat belts for 30 years, until forced to wear one as a policemen. I have to say, I thought they were an unnecessary encumbrance until their efficacy was reaffirmed at the scene of my first serious accident investigation. The folks wearing seat belts lived.
I will ask in this forum, what I have asked in all others; please name a plumbing code that allows open systems? |
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MA
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jmagill
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| 03/10/2009 2:27 PM |
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The next person who owns my home will not have to worry, It is plumbed and ready to go closed and will be the day I leave this home.
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BadgerBoilerMN
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| 03/10/2009 2:36 PM |
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| You lost me. If it's ready to go, why use it as an open system to start with? |
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MA
www.badgerboilerservice.com |
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jmagill
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Posts:237
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| 03/10/2009 3:00 PM |
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As it is I use one heating source. It will need two sources or one more expensive system. The other option would be heat exchanger and loss of efficency.
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