Water Head Calculation and Circulation Pump Questions.

[th3w01f]

Been dealing with domestic hot water issues for the last 24 hours (ever since the boiler guy left on Christmas eve). Boiler is functioning fine but I believe we had an air lock in the circulation pump (Taco 003). I disassembled the pump to verify it was functioning and after putting it back together we now have circulation again (judged by the pipe temperatures at the far end of the house, which had dropped to room temp but are now back up to about 120 or so.

After reading more on the 003 it's only rated for up to 4.5 feet of head and I'm not sure if that's near enough.

Here's a crappy drawing of what we have going on (left off the boiler loop).

Blue is cold in from the well
Red is hot
Red is 3/4 copper throughout most of the house but is stepped down to 1/2 somewhere between T2 and 003 (finished basement so I don't see where it happens.

Boiler heats tank 1 (T1) in boiler room.
T1 provides hot water to most of the house and also to T2 at the opposite side of the house (~80' away).
T2 provides hot water to the Master and one secondary bathroom at the far side of the house.
Taco 003 circ pump is about 6' from T1 and mounted about even with the top of T1.
Out of the 003 drops about 3' and goes into the cold water line filling T1
Hot out of T1 has to go up about 6 - 8' to where it is distributed through the house.

Questions -
Does this design make and sense and if not what would you change?
Is 4.5' of head on the 003 enough or should it be replaced with a 006 which has 9.5' of head

Attachment 68505

[DFBrews]

your flow out the faucets comes from the well head pressure .
The circulation pump appears based on the drawing
it is pulling water from t2 back into t1 to be heated by the boiler again to get your master water hot quicker

[DFBrews]

Any pictures of the actual setup?

[th3w01f]

Your description of the flow is correct, here are the pics.

Taco pump is just about center and that is T1 in the main room. T2 is in a closet at the other side of the house.

Distance from top of T1 & T2 to the main pipes in the ceiling is about 6'.

Attachment 68506Attachment 68507

[DFBrews]

Ah Someone got a new expansion tank for Christmas

[th3w01f]

Ah Someone got a new expansion tank for Christmas

LOL, not the gift I was hoping to buy for myself. ;-)

[DFBrews]

Here is a PDF explaining head pressure in a closed loop system.

basically head pressure in a closed loop system is only friction flosses from fittings lines etc

i bet you got air locked on the circulation loop and it is now purged are there air bleeds anywhere in the system ?

http://www.michiganair.com/newslette...2/section4.pdf

[th3w01f]

Here is a PDF explaining head pressure in a closed loop system.

basically head pressure in a closed loop system is only friction flosses from fittings lines etc

i bet you got air locked on the circulation loop and it is now purged are there air bleeds anywhere in the system ?

http://www.michiganair.com/newslette...2/section4.pdf

Thanks for the info, I"ll check it out. The first part along with your statement makes it sound like head isn't an issue on the circ loop.

No air bleed but we have the bib just to the right of the 003, the boiler guy added the bib to help drain air and a check valve between the bib and 003 since it seemed that we were getting some cold water back into the system. With the check valve there I'm not sure opening the bib did anything to help the air lock if it was at the pump, but when we took the pump apart it fixed the problem.

Now that I somewhat understand what's going on, I don't see where that check valve on the input side of the 003 adds any value since the only way cold would be coming that direction is if the 003 wasn't functioning at all.

Any thoughts as to why we'd be getting ghost flow on the pipes to the zones? Even when the thermostat is off and a zone hasn't called for heat in days, both out and return are about 180. Same with all the zones that aren't physically shut off. Boiler guy said it would require a re-pipe to add priority for the hot water but I have no idea if that's correct. He didn't want to do a re-pipe so I don't feel like he was trying to up-charge me, he just said that was the only way to completely fix it. He just suggested keeping the thermostats lower than we want the temp to be and physically shutting down all the zones in the summer.

Thanks again for all the help!

[Erni]

If I am seeing this correctly your boiler draws from t1 and the water then passes past the heating returns. Output from boiler goes past heating supplies and into t1. If this is correct your inputs and returns will hit the same temp over time. As long as there is no actual flow into the heating circuits, it should be fine.
In a closed system your head losses will be minimal, and the lack of pump head would only sliw down rate of t2 getting hot water.
The thing that is odd with your system is the cold water feeding into the tank, nad not going to the boiler first. I think I would feed it in after the heat returns and before boiler input to maximize heat transfer efficiency.
This is all going from what I learned in school a few decades ago, so it is open to review.