open systems

ed wallace

I am rewiring hydro air systems in an apartmnt complex in eastern Ma. hot water for hydro airs are provided by gas water heaters that have side tappings for heat just found out these side tappings are not isolated from domestic hot water now i finally understand why the apartments never get warm enough in winter just glad i do not live there

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Firedragon_4

That install is illegal in MA

unless it has been specifically approved by a state inspector. If you need a name at the Board let me know.

I hope you know what you're doing Ed, I wouldn't have touched it and ran like hell, JMO!

hr

You may be

looking at the State brand Apollo system. Thousands of these were installed for applications like that. i believe they are still available.

I like to see them installed with a good thermostatic mixer on the DHW supply. This allows you to crank up the temperature to get the performance you need from the hydro coil, yet address the scald potential.

While not my favorite install, they can and do work well IF installed and adjusted properly.

The amount of water in the hydro coil and piping when located next to the tank if very low, and the temperatures are usually much higher than an open radiant system.

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Dave Yates (PAH)

good points

and true - but only when running. The rest of the time, they offer Legionella all that's needed for rampant reproduction.

If a simple shower head is listed as something that needs to be treated, and it is for hospital systems, and it holds a minimal amount of water - yet sees much more "exercising" during summer months than does an open potable/hydronic system - then I have doubts about the integrity of any open system that incorporates hydronics.

I do agree, however, that other types of open systems are a greater concern. Your point about installing a certified ASSE 1017 point-of-source thermostatic mixing device is absolutely correct. CYA (Cover Your ****-sets)

All that's missing are the ASSE 1016's at all points of use and constant circulation in the potable distribution network(G). 140 or higher in the POS; 133 min in the DN; 110 or code mandated setting at the POU; and 122 min at the POS return tapping from the constant circulation.



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hr

This would be an excellent

application for ME's venturi system. Such a small capacity system could get a complete "volume turn" with a simple non mechanical, non electric devise.

I understand the concept of constant circ DHW and point of use mixers. It will add initial cost, plenty of lifetime maintenance and repair cost, and increased energy consumption for both the pump and heat loss thru even insulated pipes.

I suspect in the future this will be a required installation. Seems like a lot of technology for safe DHW

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bob_25

fire protection

Dave, I saw an article somewhere about residential sprinkler systems and it mentioned that nfpa approves two kinds of systems closed and open. I went to nfpa site and found out the code is 13-D but you have to buy the book to see what it intails. What's your take on these systems? bob

bob_25

Hot Rod

I used to service a Ramada Inn in Glnwood Spgs. Co that had an open system. I don't know how safe it was but the big problem was wearing out return bends on the heating coils. bob

hr

Bob, being a westerner

or former one, I know for a fact much or the water out there is real close to sand blast media!

Isn't that area famous for the sulpher water also? Maybe you had a sulphuric sandbalasting action going on

Of course overpumping will wear bends out like that. Another common problem when plumbers oversize DHW circs. They tend to wear the curver out of the elbows first.

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bob_25

Our Water

in G.S came out of no name creek. I don't know how many grains but it wasn't bad. The mineral in a closed system is minimal and it settles out and the oxygen combines with the metals and disappears as long as the system is REALLY closed. I think when you are constantly introducing fresh water with it's minerals and oxy. the water is more agressive. I know the first pipe to wear out in most condo complexes is the domestic hot water recirc line. If you send a sample to the copper development institute theytell you it's erosion corrosion caused by high velocity and not reaming the pipe. I have worked on a lot of closed systems with continious circulation and don't recall many erosion problems. bob