circ pump basic question

allenh

Does a circ pump as it ages have reduced flow? Talking specifically about a taco 007 on supply side of a super store. Its running, there is no air, but recovery time seems to be longer than when it was first installed.

kpc_50

circ. is not ....

losing flow but I bet the coil is probably losing its ability to transfer heat... If you are on a well or just plain have hard water the coil will scale up and insulate the heat transfer. Recovery times will be longer. A solution is to flush the coil w/ acid to get the junk off...kpc

chris_93

007 pump

Without knowing the rest of the system a 007 on most super stores doesn't have enough head to give full btu potential of boiler.
Most super stores req a 009 to achieve full potential, provided it's hooked to a boiler with enough btu's.

Also is this zone priority it's been cold last few weeks and heat may be on as well.
We need a little more info.

allenh

circ pump basic question

Burnham 209 gas boiler ( I think that output is around 218k btus). Has 5 zone controller with the priority ON for making domestic hot water. Apts are all small 2 bed units, each around 725 sq feet. This set up has worked for ~ 16 years even though its only 40 gal superstore. I think that its the original pump on the indirect.
Yesterday we were trimming out a second superstore and noticed the original one took longer than normal to replenish itself. That is why I was wondering about the circ pump losing power and now I am wondering about the flowcheck. Is there any way to clean this tank other than emptying it?

chris_93

Your response leads to KPC diagnosis. I seriously doubt its the flochecks or pump.
The coil in the bottom is loosing its ability to transfer heat to the water tank. You need to clean to coil in the tank.

steve_199

Coil testing and cleaning instructions...

On 8/24/07 Ted Gregoriadis posted a link on The Wall to an HTP article about troubleshooting indirect water heaters that included instructions about how to test an indirect coil, and how to clean a limed coil with thermal shock, CLR or Lime Away.

Although I can find the link with a search of The Wall, the link isn't active, and I can't find the article on the HTP website.

Here is a brief summary of the recommended test:

To test the coil: 1. Shut off the boiler, 2. Drain the entire contents of the indirect, 3.Refill the indirect with new cold water, 3. Turn on the boiler. The temp entering the coil from the boiler (normally 180 deg)should be at least 30 deg higher than the water exiting the coil for the boiler. if the delta T is much lower the coil is not transferring and will need cleaning.

To clean the coil with thermal shock, drain all water from the indirect and let the hot boiler water pass through the "dry" coil for 10 minutes. Turn on the cold water into the indirect for 3 to 5 minutes so as to cover the coil. This causes the hot coil to contract and deposits to flake off. Flush the water out of the indirect and repeat the process. Thermal shock cleaning may not be effective if the deposits have been on the coil for a long time, in which case HTP recommends chemical cleaning.

If I can find the linked article I'll post it.

allenh

indirect

How often should an indirect be cleaned? This has never been cleaned in ~ 16 years. Its city water from Mass Water Resource Authority.