OPEN SYSTEMS not trying to open up a can of worms.....

Joe_51

I'm close to finishing up my DIY radiant floor/ceiling system in the new house I am building.I'm using a WH for both my domestic hot water and my radiant heat source. I had planned on using a heat exchanger to separate the closed loop radiant system from the domestic side.I've read alot of negative thoughts of the open systems from guys in the field on this site and others. I lot of the cons I think were about liability. CYA. I agree with most of the cons by the way. I'm tight on money at this point of the game so I"ll throw this one out there.....We live in a northern climate(Maine) which I can forsee using thr radiant system up to 9 months of the year( heck...it was/has been in the 40's until a few days ago, wood stove burning) so stagnet water sitting in the pipes possible would only be 3 months of the year. What if I added a timer into the system that called for heat(circulated water) so often. Would this fully address the stagnet water issue?The house in question is our house and an fully aware of the possible dangers if this system wasn't "flushed" .Is there anyway to use a open system safely????Joey

Maine Ken

It is unlawful in Maine to install an open system. Homeowners as almost always can do whatever they want by themselves. I think you will have a difficult time getting anyone to service this system once it is in. I don't know of anyone willing to work on them.

"Maine" Ken

kevin coppinger_4

why don't you...

put in two seperate water heaters? by the time you get doing all the recirc., timer and stuff your talking the same $... kpc

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Dan Peel

To Borrow

I like ME's approach. There is no right way to do it wrong! Thanks Mark.
Enjoy.....Dan

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Paul Pollets

With your climate...

you'd do well to consider a boiler, rather than a water heater, for many reasons. If cost is a concern, than consider the long term energy savings a condensing boiler could deliver.

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Maine Ken

Or even a cold start, low mass, 3-pass boiler w/ indirect.

Weezbo

Are you on \"City\"water?

If so, some day, you may be letting yourself into a lawsuit. it is perplexing to say the least as how to see the easiest means to help you. were you able to dissasociate the potable water from the heat by running new hot water lines and a seperate heat source for it depending on the backflow placements and checking any chance of cross contamination as it is called,i think you would be a Ok. mixing valves etc arent likely to be considered a reliable means of isolation.

DaveGateway

If you want safe and cheap

Just get a High input direct vent energy saver WH from Bradford WHite.

Constantin

Joey, fix it as soon as you can

...as a fellow homeowner and part-time Mainer, I can relate to why you are trying to save a few $$$ by using a single open system. However, as other folks have pointed out here, you may be looking at false economy when you think that a purely open system is the way to go.

If you look through the many posts here with evidence from folks here to the pitfalls of open systems (like them eating ferrous components for lunch), the added risks of legionella, etc. just don't seem to justify the risk. Your plate heat exchanger may be all you need to keep the two systems separate. I'd separate them in a hurry!

Instead of going with an open system off a WH, I would look into getting a subsidized loan to improve the energy efficiency of your home. Over the long term of a mortgage, the monthly energy savings of a condensing boiler over most water heaters will pay for itself, particulalry if you're using propane to heat.

Circulation by itself will not kill legionella, so I have read. Only consistent water temps in excess of 130-140°F will do that. With an open system in the summertime, your house will not only become a sauna, your heating bill may approach "interesting!" as well.

Legionella and other bacteria is why many folks here advocate hot potable water storage tanks to be kept at 140°F and a mixing valve to temper the water down to 115-120°F once it leaves the tank. Not only does this extend the hot water capacity of the tank somewhat, it also kills off the nasties.

Joe_51

You guys killed that idea.

Someone said that you guys in the field like to keep hot water at 140 degrees and use a tempering valve to mix it down to 120 degrees to kill the nasies...In the mid alantic area (where I am from) I have NEVER in my like seen anyone do it that way. No one uses boilers to generate those temps to begin with, everyone uses nateral gas or electric water heaters set to 120 or so. Never heard of anyone getting sick.Anyway....I'll reconsider the HX. Thanks for so many replies.

Dave Yates (PAH)

ANSI Z21.10.1

No matter how you feel about storage temps, the move to reduce them to a factory setting of 120 (instead of the 140 they used to be set at by the factory) has not reduced the number of scaldings and deaths caused by hot water in the US. Over 100,000 scalding cases and several hundred deaths per year are attributed to potable hot water. At 120 F 3rd degree burns are still a reality in just over 3 minutes of contact time. Infants are four times as susceptable due to their thin skin. Elderly and infirm users often lose sensitivity to hot water burning. Diabetics often can't tell if the water is hot.

ANSI Z21.10.1 regs currently allow for stacking temps as high as 190 F in residential water heaters (where their stat is set for 120 F) of 75-gallons or less. Obviously, a 3rd degree burn is possible in the wink of an eye with a 190 F delivery temp.

An ASSE certified thermostatic scald guard mixing valve should be mandated for codes compliance on the outlet to the potable distribution system.

It's common sense, but it's not required - yet.

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bill clinton_3

\"never seen anyone get sick\"..from legionella

The appropriate counter argument is "How do you know you haven't seen people getting sick from legionella?"

You have seen people get short-term "flu" haven't you? A large proportion of those exposed to concentrations of legionella (I've seen 90% cited) develop flu-like symptoms. This is known as "Pontiac Fever", although it is rarely diagnosed because diagnosis is a complicated, expensive proposition and it is after all, just "the flu" Victims are the healthy people with strong immune systems.

So, Pontiac Fever could be all around you and there would be no way to know.

The same applies to Legionnaire's. Elderly and immune-compromised get Legionnaire's. It is almost always diagnosed as pneumonia, which of course, it is.

Pneumonia is fairly common. It is one of the most common ways for elderly and immune compromised to die. Elderly and otherwise weak individuals have a habit of dying from one thing or another eventually. Death from Pneumonia is
almost "normal." Very rarely is the source of the pneumonia tracked down. It's a difficult and expensive process and the victim is often already dead, so what's the point?

The point is that in cases of "outbreaks" where a significant number of people are brought low with the same symptoms, investigation gets done. There have been numerous hospital/hotel outbreaks where the detective work shows the legionella to have infected the hot water supplies. Those hot water supplies offer conditions very similar to "open" radiant systems: Conditions very favorable to the legionella bacterium.

Given all this, and given that most of us know of cases of severe pneumonia and probably of deaths caused by pneumonia, I ask you: How do know you've "never heard of anyone getting sick" from these systems. Seems to me it's fairly likely you have: There just wasn't a way to make the connection.

Not meaning to pick on you. Maybe the advocates of open systems are right and they're perfectly safe. The evidence available so far leads me to believe they're not.

Bill

Dave Yates (PAH)

Beautifully said!

Next beer for you is on me pal. (ISH-NA?)

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Joe_51

stong case for closed systems

Bill ,you make a good point.I don't think someone informing me is picking on me.I'm swayed back to the closed system again. I just hoped there was a way to save a little $$$ on my install. As for the post about an anti scalding valve...that's a no brainer.