External Gas Heater Hookup On Healthy Living Master Spa Tub

[4free]

I need some help re-installing my external Raypak gas heater on my hot tub. I originally had a 2003 Master Spa Legend LS800 that I had spliced the 2" output of the circ pump to the gas heater, then back through the internal heater. That meant I could used either heater for the tub at any time. Unfortunately, the breaker tripped a couple of years ago during the winter (during a power outage/surge) and ended up freezing the pipes.

I have replaced the tub with a 2015 Master Spa Healthy Living tub. Unfortunately, I cannot plumb it the same way for a couple of reasons:

• The circ pump on the new tub is a 'high efficiency' pump with only a 1 1/4" output which would not give me the required flow rate on the gas heater.
• They have also reversed the flow so that the circ pump "pulls' from the heater, so both heaters would be kicking in if the I plumbed it in the same spot.

I am looking at adding an additional pump just for the gas heater that would only kick in when the heater is running. My questions are:

• What pump should I get (size, brand)? I prefer to keep this one 110v and use the same 2" in/out as the heater.
• Where should I splice into in the line of the tub? The heater is physically located on the left side towards the rear of the tub, looking from the control panel. There is an empty space inside this area with room for a pump.
• Should I install a fireman switch on the pump, to keep it circulating after the heater shuts off? How would i wire it to the Raypak?
• Is another option to install it inline with one of the 2 main pumps and forgo the additional pump? What are the +/- of that? The tub uses a Balboa BP501 series controller.

Thanks for your help.

[4free]

No ideas???? Anyone?