Reading the forums here I knew that I wanted a bypass for the heater. We settled on the Pentair Ultratemp 140 - the biggest one available. The PB tells that the heater already has an internal bypass built in so we don't have to plumb for an external bypass. How true is that?
Internal heater bypass
- Thread starter sourabhdeb
- Start date
panic_button
Bronze Supporter
- Jun 23, 2019
- 352
- Pool Size
- 21000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Your PB is correct the heater does have an internal bypass,but that is for water flow to the coil. You also want an external bypass for use in service or if there is an issue with the heater, and it's cheap insurance ($100 for the required parts). We had an issue with our heater and for 3 weeks we had to bypass the heater while the replacement was in route, without an external bypass the pump would have to be off for that time frame.
- Jul 21, 2013
- 53,925
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
I realize this post is old- We just got a pentair mastertemp 400. I looked up the manual and believe the bypass valve is not used to bypass water when the heater is not being used. In fact from the design- it appears that when the flow increases- as it will during the heater usage- excess flow is diverted away from the heater core. So during normal operation- mid to low speed- no water is being bypassed and flowing through the heater.
- the external bypass as described here ( Pentair MasterTemp Heaters - Further Reading )- is necessitated when flow to the heater might exceed 120 gpm .
- the external bypass as described here ( Pentair MasterTemp Heaters - Further Reading )- is necessitated when flow to the heater might exceed 120 gpm .
I’m trying to understand this as will with my Mastertemp 300. Adding a VSF pump and wondering to do manual or automatic external bypass or if my heater does good enough job with the internal bypass.
Vsman - your assessment seems correct to me. I wish Pentair manual was more clear.
- Jan 7, 2012
- 1,550
- Pool Size
- 21000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
I would strongly recommend installing an external bypass. Aside from giving you options and flexibility, it will significantly improve the efficiency of your system when you aren't using the heater.