SPA heater, what would happen?

[Hulaomr]

Hello @JamesW,

I was talking with a local expert in ducts and vents.
Attached a proposal considering stainless sheet with thermal isolation around the concrete space.

The idea is to open the ceiling and create a concrete edge (as shown the drawing) with a couple of inch of clearance between the metal and the concrete, where the thermal isolation will be installed. A little metal net will be installed (welded) and the vent termination.

Please, let me know what you think about it.

Thanks!

 

[JamesW]

I don't know enough about venting to give a good analysis.

Maybe check with Pentair to get their opinion.

Customer Service

Contact Pentair for information regarding our sustainable water products and solutions or for more information on our global company.

www.pentair.com

 

[Hulaomr]

Hi @JamesW

I finally build the exhaust and supply air intake as suggested and discussed previously. Below a picture with both.



After the installation, the noise (from the blower) reduce a lot. It now take air from outside the room (3" PVC pipe) and remove the gases to the roof (7" galvanized metal custom pipe) as show in previous proposal.

A new test was performed in this conditions, recording the gas consumption and temperature increase. A total time of ~24 minutes to increase from 29 to 40 degrees Celsius as show the table below.






Appreciated your feedback regarding the results.

 

[JamesW]

For 580 gallons, you should get about 70 degrees F per hour or about 1.16 degrees F per minute.

You are getting about 20 degrees in about 24 minutes, which is 0.833 degrees per minute.

This is about 72% of the expected value.

A total time of ~24 minutes to increase from 29 to 40 degrees Celsius as show the table below.

You should get about a 0.65 °C per minute temperature rise in the spa.

11/24 = 0.46 °C per minute.

That is about 71% of expected value.

 

[JamesW]

You should use about 4.5 cubic meters of propane per hour for a 400,000 btu/hr heater, which is about 0.075 cubic meters per minute.

You should use about 1 cubic meter per 13.3 minutes.

You used 1.4 cubic meters in 24 minute.

This is 0.05833 cubic meters per minute or 3.5 cubic meters per hour.

3.5/4.5 = 78%

 

[JamesW]

Heat exchanger on Raypak

Hi, I’m new to this forum and I’m trying to figure out why my heat exchanger on my Raypak for both pool and spa are going out or bad after a years use having condensation run down the stacks and into the unit!!???? The heat exchanger are not chemically damaging themselves from the inside out...

www.troublefreepool.com

 

[JamesW]

The heater exhaust should be noncondensing, which means that the exhaust temperature should remain above 132 degrees until it exits the vent.

If the exhaust cools too much, the water vapor could condense and go back into the heater.

The combustion of Propane produces water vapor.

C₃H₈ + 5O₂ -- >3CO₂ + 4H₂O

Propane + 5Oxygen --> 3Carbon Dioxide + 4Water.

Normally, you need a draft hood unless you use a power vent.

I cannot give good and complete advice about venting, so this is just general reference information.

Review this other thread for some general discussion.

Heat exchanger on Raypak

Hi, I’m new to this forum and I’m trying to figure out why my heat exchanger on my Raypak for both pool and spa are going out or bad after a years use having condensation run down the stacks and into the unit!!???? The heat exchanger are not chemically damaging themselves from the inside out...

www.troublefreepool.com

 

[Hulaomr]

The heater exhaust should be noncondensing, which means that the exhaust temperature should remain above 132 degrees until it exits the vent.

If the exhaust cools too much, the water vapor could condense and go back into the heater.

The combustion of Propane produces water vapor.

C₃H₈ + 5O₂ -- >3CO₂ + 4H₂O

Propane + 5Oxygen --> 3Carbon Dioxide + 4Water.

Normally, you need a draft hood unless you use a power vent.

I cannot give good and complete advice about venting, so this is just general reference information.

Review this other thread for some general discussion.

Heat exchanger on Raypak

Hi, I’m new to this forum and I’m trying to figure out why my heat exchanger on my Raypak for both pool and spa are going out or bad after a years use having condensation run down the stacks and into the unit!!???? The heat exchanger are not chemically damaging themselves from the inside out...

www.troublefreepool.com

View attachment 628945

View attachment 628946

Good point. I will review about the comdesantion.

Thanks for your feedback. Appreciated.