Radiant heat question

Ok guys. I've spent several hours and I think I finally found the 1st prob. I closed 3 of the 4 zones and put a bucket under the spicket on the return side and opened it up. After 4-5 buckets of still cold water barely coming out I unplugged the relay feeding the garage zone and the water pressure or lack of didn't change. So I believe the pump is running but not pushing water. I figure that with the system return piped in feeding a lot of back pressure the water isn't circulating at all.

My next ? Is can I put a taco 007 circ pump onto the same flanges? Or should I use a bigger pump? Thanks for all the help and support.

You need to replace that faulty mixing valve. As for the circulator, it is tough to size one without knowing how long the pex loops are. If they are 250/300 feet long, it seems like a Taco 007 or the like would have a hard time overcoming the resistance to flow. I would experiment with a larger pump.

What would be the next size up from a taco007? Sorry but I'm new to the home owner world and it's true what they say. A mans home is his hassle

Read my posting on how to size circulator pumps.

Yanche's Toolbox, Piping & Circulator Selection Method

I've also posted pump curves for different Taco pumps. Don't buy anything until you understand what piping you have and what amount of heat you are trying to put into the slab. You will need to do some engineering. Guessing will be much more expensive.

Another question for you guys. I just noticed that there is an arrow on the face of the pump showing counter clockwise. Is this the rotation of the pump? If so that would mean the circ pump is running backwards and would be pushing towards the mixing valve and pulling water from the 1/2" pipes and the return side. Do they make clockwise pumps? Ccwise is correct on all my other zones but not this one. Is it possible this zone has never worked. Actually now I think of it when the plumber replaced one bad mixing valve for another it was upside down and he rite side uped it. Could this be my prob? I'm more confused now then before I started

taco 0011 has a much larger impeller than 007. seems like inadequate water flow rate. be sure pump is pulling out of mix side of tempering valve. I have had to add 2nd pump,push-pull if tube runs are excessive.

Rob R. wrote:You need to replace that faulty mixing valve. As for the circulator, it is tough to size one without knowing how long the pex loops are. If they are 250/300 feet long, it seems like a Taco 007 or the like would have a hard time overcoming the resistance to flow. I would experiment with a larger pump.

Would this be a good application for a variable speed delta t pump.?

chevymatt wrote:Another question for you guys. I just noticed that there is an arrow on the face of the pump showing counter clockwise. Is this the rotation of the pump? If so that would mean the circ pump is running backwards and would be pushing towards the mixing valve and pulling water from the 1/2" pipes and the return side. Do they make clockwise pumps? Ccwise is correct on all my other zones but not this one. Is it possible this zone has never worked. Actually now I think of it when the plumber replaced one bad mixing valve for another it was upside down and he rite side uped it. Could this be my prob? I'm more confused now then before I started

I saw that arrow in one of your pics and wondered the same thing? I would have to think that yes the arrow indicates motor rotation... But does motor rotation necessarily indicate flow direction? Obviously the rotation of the motor one way or the other does dictate which way it will pump fluid... If in fact it is pumping the wrong way the motor housing will be blazing hot to the touch and it won't last too long like that... A deadheaded pump in not a happy one...

EDIT: Just looked up your pump, that arrow is the motor/impeller rotation... In your case you are pumping toward the mixing valve.... Flip the pump if you have enough room to do so?

There is an arrow cast into the housing or impeller side of the pump that indicates direction of flow... That pump IS a 15-42, the equivalent to a 007 is a 15-58.... I'm thinking you have a pump issue, how long of a run is the 1" from the photo of the mixing valve and circ to the manifold?

MoBe wrote:There is an arrow cast into the housing or impeller side of the pump that indicates direction of flow... That pump IS a 15-42, the equivalent to a 007 is a 15-58.... I'm thinking you have a pump issue, how long of a run is the 1" from the photo of the mixing valve and circ to the manifold?

From the mixing valve to the manifold in the garage is probably 75' give or take. It appears that the 1" is the return and it's pushing into the mix side of the mixing valve and out the cold water side to the 1/2" pipe

chevymatt wrote:

MoBe wrote:There is an arrow cast into the housing or impeller side of the pump that indicates direction of flow... That pump IS a 15-42, the equivalent to a 007 is a 15-58.... I'm thinking you have a pump issue, how long of a run is the 1" from the photo of the mixing valve and circ to the manifold?

From the mixing valve to the manifold in the garage is probably 75' give or take. It appears that the 1" is the return and it's pushing into the mix side of the mixing valve and out the cold water side to the 1/2" pipe

I said to flip the pump in my previous post, don't flip it, just rotate it 180 in its flanges if you have the room to do it...

MURDOC1 wrote:

chevymatt wrote:

MoBe wrote:There is an arrow cast into the housing or impeller side of the pump that indicates direction of flow... That pump IS a 15-42, the equivalent to a 007 is a 15-58.... I'm thinking you have a pump issue, how long of a run is the 1" from the photo of the mixing valve and circ to the manifold?

From the mixing valve to the manifold in the garage is probably 75' give or take. It appears that the 1" is the return and it's pushing into the mix side of the mixing valve and out the cold water side to the 1/2" pipe

I said to flip the pump in my previous post, don't flip it, just rotate it 180 in its flanges if you have the room to do it...

I will try that tomorrow. Thanks for the help. I'll keep everyone posted

chevymatt wrote:I will try that tomorrow.

If it ends up that you don't have enough room to rotate the pump: you say that you need to replace that mixing valve anyway? This would be the time to do it and instead of installing it with the outlet parallel to the wall have it face out at 90 degrees from the wall, short stub out of the outlet then turn 90 degrees toward the wall that your supply/return piping is coming through. That will then give you plenty of room to rotate the pump... If you end up doing it this way just be sure to support the mixed water run from above or otherwise...

Just to clarify another issue Matt, could you detail which of the two Pex lines is the supply and which is the return. Also, take the pump cartridge out and inspect the impeller. There are 4 little bolts or screws around the perimeter of the pump that hold the cartidge in. It is simple to take the pump apart and make sure it isn't plugged. Make sure you close the valves off so you don't lose coolant.

Scottscoaled wrote:Just to clarify another issue Matt, could you detail which of the two Pex lines is the supply and which is the return. Also, take the pump cartridge out and inspect the impeller. There are 4 little bolts or screws around the perimeter of the pump that hold the cartidge in. It is simple to take the pump apart and make sure it isn't plugged. Make sure you close the valves off so you don't lose coolant.

You may be onto something there, but either way he is pumping toward the outlet of the mixing valve... I can't imagine those valves like to flow very well if at all backwards? My guess is that the 1" pex is the supply to slab and the 4 smaller 1/2" (?) are the returns from slab? Would make sense for it to be that way, but Matt will have to verify...