Low Inlet Pressure to Hayward 400K natural gas heater

stephenson

Well-known member
Nov 30, 2009
136
So, quick check this morning - static starts high, but stabilizes at 9.62, then drops to 7.25 when running.
 

JamesW

TFP Expert
Mar 2, 2011
28,255
Ok, that seems better.

Maybe some bleed through while it's off.

I don't know if that could be an issue long term as far as possibly damaging the heater's gas valve.

Maybe ask the installer about the initial high reading.
 

stephenson

Well-known member
Nov 30, 2009
136
If the regulator says it is set to 8”, how could it provide 9.62”? I watched the tech unseal the box.
 

JamesW

TFP Expert
Mar 2, 2011
28,255
If the regulator says it is set to 8”, how could it provide 9.62”? I watched the tech unseal the box.
Every specification has an allowable tolerance.

Between the tolerance of the regulator and the gas pressure manometer, it will be slightly more or less than the specifications.

The service person might have adjusted the pressure, but that should not have been necessary.

Also, it was pointed out that the regulator is not the best quality.
 

stephenson

Well-known member
Nov 30, 2009
136
Service tech did not adjust - I watched the regulator box unsealed and the installation. I fully understand the engineering required and concept of tolerances, both manufacturing and operations - but this equates to around 20% ...

I pulsed the tech yesterday on the pricing - he is standing by their cost of $198.40 for the regulator ... everywhere I look it is $60-80 :)
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
18,605
Tucson, AZ
Pool Size
16000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
I’m sure the gas regulator is good enough (overpriced and marked up but good enough). You’ll get a few good years of life out of it and then you can always replace it with something better later. Don’t let the pursuit of “the perfect” be the enemy of the “the good”. Just make sure the regulator model you have provides enough gas flow for the appliance so that it’s not limiting your flow rate. We had a gas furnace that struggled for a while when we first moved into our home. I had several different “technicians” come out and they all shrugged their shoulders and gave half-cocked excuses for why it was normal and why I was being too picky. They also spent most of the service visit just trying to sell me a new furnace instead of trying to figure out what was wrong with the one I had. After three different companies came out, I decided to take matters into my own hands and within about an hour of poking around the equipment and reading online service manuals I discovered the regulator on the gas pipe was too small for the unit. Whoever did the original equipment installation put a regulator on with too low of a flow rate requirement (our homes in my neighborhood are “housing craze homes” built in 2005/2006 … so they were all built like total crud by “contractors” that were more interesting in collecting their pay than doing a job right …. Never buy a home built in 2005/2006 time frame). After replacing it with a properly sized regulator, the furnace worked much better and the heater didn’t need to struggle to keep the house warm.

Long story short … you’re fine. Go enjoy your pool.
 

stephenson

Well-known member
Nov 30, 2009
136
Thank you JamesM and JoyfulNoise!

So, what I have noticed is that temp rise is faster ... maybe 4F per hour? I should have created a log previously for comparison purposes, but ...

When the heater starts - it starts! Quickly, and runs a bit more, er, robustly? Exhaust is a bit louder.

I'm not going to press further on the gas tech, but I did want him to know some folks actually check what they are buying - and, try and learn and share with others.