It always seemed that our forced air heat was slow to respond and the coil fan ran a lot whether on gas or wood. I thought I would measure all the pipe in the pre-existing system and assign equivalent lengths to the fittings and accessories to give me a total head. When I went to apply an equivalent length to the Erie zone valve to the coil I notice that the 1â€ pipe was necked down to Â½â€ and then up to a Â¾â€ NPT Erie zone valve with a 3.5 Cv rating. Head is 9â€™ at 7.5gpm. My overall head calculated to 18.85â€™ @ 7.5gpm. This being the case the installed Taco 007 is highly inadequate and incapable of delivering adequate flow to efficiently satisfy the coil. If my assumption is correct I should replace the current configuration at the 1â€ pipes and replace with a 1â€ NPT Erie valve which if I understand the information correctly would allow 8gpm @ 2.31â€™ head. This would lower my system head to about 12â€™ head at 8gpm which could be handled by a Grundfos 15-58 rather than going to a more expensive and expensive to operate pump. (Iâ€™m gambling this because my existing 007 system is incapable of delivering 8gpm but is still able to heat my house so with the new pump I should increase flow about 60%). Is my thinking and troubleshooting correct? I guess if this does not help I always have a spare 15-58 when I need one.