# Unconventionally piped systems



## CaberTosser (Mar 7, 2013)

We have some client condo towers where the developers decided to get 'experimental' and they installed a heating system that uses the domestic hot water to supply the HVAC fan coils. The boilers are fed softened water to assist in preventing hard water scale accumulation. These are 20+ story buildings. Has anyone seen similar systems in their vicinities? I'm not keen on the concept, as any issues with the system affects both the heat and the domestic hot water supply. For those of you in warmer climates who don't witness catastrophe's from freezing weather there is a back up, as every condo I've seen also have gas fireplaces in every unit, but they provide neither even nor sufficient heat for those 'design temperature' days.


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## billwestrick (Mar 4, 2013)

is it done thru a heat exchanger?

bw


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## CaberTosser (Mar 7, 2013)

billwestrick said:


> is it done thru a heat exchanger?
> 
> bw


 Nope, its domestic water flowing straight through those fan-coils.


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## alberteh (Feb 26, 2012)

why would that be a problem?


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## redbeardplumber (Dec 4, 2012)

My buddy is a service plumber in Calgary. He said they ram into one building downtown that had that. All fittings on boiler were brass and all heating (rads and hvac) was also domestic HW. 

IDK dude. That shiot ain't right


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## alberteh (Feb 26, 2012)

DHW is still hot...

done right shouldn't ever be an issue. if i remember my code something about having water cycled out min. once every 24 hours and ur good.


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## CaberTosser (Mar 7, 2013)

It doesn't sit right with me. Lets say that for some reason the heating system must be isolated for repairs; congratulations all you occupants, you've now also got no domestic hot! And BTW, we probably also had to kill the domestic cold to prevent crossflow through the single-lever faucets from disturbing our work. Have a nice day 

Maybe instead though we're fixing some domestic hot water issues; Oh Hey, the heats also off people.....

Oh, did I mention that there's no balancing valves? Who needs precisely machined parts with test ports to set proper flow rates to prevent excess flow pinholing when you can just install some globe valves and leave them wide open?:whistling2:


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## alberteh (Feb 26, 2012)

add a valve to allow bypassing of heating system while repairing if needed, kind of like meter bypass system?


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## CaberTosser (Mar 7, 2013)

I was more referring to a situation where work on the mains was required, or if isolation was necessary simply to replace faulty valving isolating a floor. The individual units are adequately isolated (at least in this particular development, which shall remain nameless)


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## thepmac (Apr 26, 2011)

I'm from edmonton and I have seen several cooling coils that are run off domestic cold lines in high rises. The worst part is there is no return water, the return side of the coil is just run to drain. Such a waste of perfectly good water. Most buildings have since added cooling towers on the roof, and any replacement cooling coils must be hooked into a closed chilled water system.


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## Plumber patt (Jan 26, 2011)

Is that not a huge cross connection? Where I'm from we have to put rp back flows on all heating and cooling make up so the heating water and domestic water can't mix..


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## CaberTosser (Mar 7, 2013)

Plumber patt said:


> Is that not a huge cross connection? Where I'm from we have to put rp back flows on all heating and cooling make up so the heating water and domestic water can't mix..


 It's not a cross connection if all the piping and components are installed with potable water compatible materials and the system only uses potable water, which is constantly replenished as fixtures are used, keeping the chlorination from depleting. The reason for the RP you're noting is that those systems will usually have steel/cast iron in them and may have glycol or corrosion preventative chemical treatments. This system is designed as fully potable.


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## rjbphd (Feb 5, 2010)

CaberTosser said:


> Nope, its domestic water flowing straight through those fan-coils.


If the water maintains at 140 or above and no sagant pocket.. its borderline okay..


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## CaberTosser (Mar 7, 2013)

The place does have opportunities for stagnant pockets though; picture in summer with the suites only running cooling and the zone valve closed to the heating coil for 3 months. Sound yummy?


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## bct p&h (Jan 19, 2013)

Just went over this in the last con ed class. It can be done but there are a ton of restrictions on it. 
The water heater must be made for space heating. 
All piping and coil must be made for potable water.
No dead ends.
Pump must be on timer set every 12 hours and run long enough to clear the lines completely.
piping cannot exceed 30 feet.
Pump must be ss or bronze

I think that's everything but I don't have the book in front of me.


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## rjbphd (Feb 5, 2010)

CaberTosser said:


> The place does have opportunities for stagnant pockets though; picture in summer with the suites only running cooling and the zone valve closed to the heating coil for 3 months. Sound yummy?


I walk away from it.. I would never subject my self to liabailty...unless Canada have " can't sue me" laws..


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## Catlin987987 (Nov 12, 2010)

There are quite a few building here in Edmonton that do the same thing.


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## Plumbworker (Oct 23, 2008)

alberteh said:


> DHW is still hot...
> 
> done right shouldn't ever be an issue. if i remember my code something about having water cycled out min. once every 24 hours and ur good.


yep with dhw through fan coils gotta have a pump exerciser to prevent stagnation in the coils.. You wire in a time switch and have it run for 60 sec every 24hrs...


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## CaberTosser (Mar 7, 2013)

Plumbworker said:


> yep with dhw through fan coils gotta have a pump exerciser to prevent stagnation in the coils.. You wire in a time switch and have it run for 60 sec every 24hrs...



I agree, though in the case of this building that would have to be a feature either built into the thermostats controlling the zone valves, or an 'exercising' timer switch wired in parallel to the thermostat. The pumps are running 24/7, we're talking 20+ floor towers here.


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