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Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 21547
Experience:  40+ yrs. experience as a licensed oil & gas technician.
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I have a Peerless Purefire installed for a customer. I keep

Customer Question

I have a Peerless Purefire installed for a customer. I keep getting an A03 lockout (overheat). It only happens when the temp goes way down. I figure it must have something to do with the circulators.
JA: I'll do all I can to help. How long have you been dealing with this?
Customer: Its been on and off for the whole two years
JA: Do you plan on doing the work yourself?
Customer: I am the installer
JA: Anything else we should know to help you best?
Customer: I spoke to Peerless about the issue. They recommended I install a different system (loop) circulator. I installed a taco 008 in place of a 007. It seemed to work, but then we couldn't get any hot water. The 007 on the hot water tank couldn't overcome the 008 on the system loop.
JA: How long has this been going on? And how severe is the problem?
Customer: If they have to reset 2 times in the night, that is serious
Submitted: 7 months ago.
Category: HVAC
Expert:  Rick replied 7 months ago.

Assuming the system is piped properly a 0010 would be a better chioce on the boiler loop. A 008 has a much steeper pump curve than a 007.

Customer: replied 7 months ago.
How about a Grundfos Alpha?
Expert:  Rick replied 7 months ago.

I don't use Grundfos and have no specs on that pump.

Customer: replied 7 months ago.
1/20 or 1/8 horsepower? The other pumps for CH and DHW are 007's
Customer: replied 7 months ago.
thats what they are selling at supplyhouse.
Expert:  Rick replied 7 months ago.

You need to look at the pump curve for a given pump. Horsepower doesn't tell you anything. Where did you get the 008? If you can get a 008 the same place has access to a 0010.

Customer: replied 7 months ago.
I looked at the pump curve. It didn't specify H.P. I was surprised to see selling the two horsepowers for the same number pump. 0010. Which do you think I should buy? It appears my trouble is that under certain full-load condition, the installed 007 in the near boiler loop will be inadequate and then the boiler overheats.
Expert:  Rick replied 7 months ago.

The DHW circulation loop may be to close to the boiler loop. I just looked and see what you mean. I wonder if it's a typo. I've never seen any Taco 00 pump model with more than 1 hp. I'd go with the 1/8 hp version.

Customer: replied 7 months ago.
its 1/20th horsepower