Jacuzzi heating up very slowly

[Highlordkram]

I just bought a new house and it has a 400,000 BTU Pentair heater but the jacuzzi has been taking hours to heat up from 48° to over 100 and my old jacuzzi with a $250,000 BTU Pentair heater would do it in under 2 hours. The spa is slightly larger but I am wondering if the valves are not in the right position as there are four of them on the system and I only had three of them before. I turned the two top valves to pool off and assume the hot water would just circulate in the jacuzzi area but I'm not sure what the two valves on the bottom are. Please see attachment and give any input you can as to what might be going on.

 

[mknauss]

Welcome to the forum.
The valves on the suction side are likely a suction side cleaner, the skimmer, and the main drain then the Spa suction. Your valve is set as shown to suction from the Spa only.
The valve on the return side is shown to return only to the Spa.

You do not provide any volumes so it is not possible to provide you the estimated time for a specific temperature rise.

 

[ajw22]

Welcome to TFP.

Look at your house gas meter and confirm it is over 400 CFM, preferably 600-900 CFM. We have seen many 400K BTU heaters installed with 250 CFM gas meters, which limit gas flow and heater output.

Post pictures of your gas meter and data plates on it. Also, show us a picture of the heater gas line connection.

 

[1poolman1]

I just bought a new house and it has a 400,000 BTU Pentair heater but the jacuzzi has been taking hours to heat up from 48° to over 100 and my old jacuzzi with a $250,000 BTU Pentair heater would do it in under 2 hours. The spa is slightly larger but I am wondering if the valves are not in the right position as there are four of them on the system and I only had three of them before. I turned the two top valves to pool off and assume the hot water would just circulate in the jacuzzi area but I'm not sure what the two valves on the bottom are. Please see attachment and give any input you can as to what might be going on.

Does the spa overflow when the valves are set to "spa" only? If so, either the suction valve in front of the pump is not closing completely or the diverter needs to be replaced. You would be continuing to pull some cold water from the pool and put it into the spa. It would be amazing that you could actually get to 100 degrees.
Do you hear a whistle-sound at the heater? If so you could have too small a gas meter. Do you have a corrugated flex gas line feeding the heater? That would/could cause the issue as well.