Insulating PVC or CPVC domestic water lines?

[doopedeng]

Hi All,
I have a hotel project in Eastern Canada where the contractor is proposing to use Xirtec 140 Sched 80 PVC piping for the cold, and Corzan CPVC for hot and hot water recirculation lines that would be UN-INSULATED throughout the building. This building is not classified as a high building and therefore the pipe is permiteed by the codes. However, I see two problems that might arise:

1. Condensation on the cold water lines - Although, most CPVC installation don't really require insulation to prevent sweating... is it the same for PVC?

2. In terms of energy consumption, there will be heat loss in hot and recirc. water lines - Even though the thermal conductivity of plastic piping is much less than copper, won't the hot water lines still lose the heat? Especially during the night when little water is being used?

So, the million dollar question here... Should the PVC/CPVC be insulated on domestic water lines?

Thanks in advance for your input..

Dooped

 

[Zapster]

Go to

http://www.pipeinsulation.org/

and download the program 3E Plus. This program will allow you to quickly investigate your questions.

For condensation, it depends on your RH, OAT, fluid temp, etc.

For heat loss, it depends on how much you value the energy that is lost. Keep in mind that energy from hot domestic water might not be lost during building heat demand; but in contrast may be multiplied during building air conditioning demand.

Use the program 3E Plus to “do the math.” As an engineer you should be able to quantify the energy usage and make a cost/benefit analysis for energy usage.

 

[doopedeng]

I downloaded the 3E program and the result indicates the nearly identical Btu/h losses for both bare and insulated copper and PVC at 140F DHW temp. I didn't really expect that result, but I'm wondering if I should have expected it! Given enough time, the pipe will heat up to the same temp regardless of material. Thoughts? Comments?

 

[KiwiMace]

I think it is a given to insulate hot and cold water distribution pipes. Check your energy codes.

In humid areas, it is standard practice to insulate PVC (or any other material for that matter) HVAC condensate drains out of the building to prevent sweating.

Sag is a big problem with PVC pipes. Make sure the supports are well designed and well built.

 

[KiwiMace]

Sorry, re-read and caught the 'domestic' part. Your cold water would normally be ok, but do a simple condensation calc to check if the surface temp drops below the dewpoint of the humidity levels you get in the area.

 

[rconner]

Having heard it can get a little cool up there north of the border, I wonder also if a little insulation might provide at least some more level of marginal security when the building heatoing system fails? Maybe other types of pipe/and/or safer to heat/trace etc. might provide even more security in this regard?