Replacing an old heating system

hot_rod

8 loops total? so at 1 gpm per loop 8 gpm, short loop, open baseboard, that pump should handle that 8 gpm at 8-10' head. 1" copper is fine, the manifold trunk size is adequate.

Some where you have a restriction, what do the flowmeters read?

Maybe the impeller in that old pump has deteriorated?

mattmia2

Are you sure the circulator is running (I don't see how you could miss it with that motor). Is the shaft coupler intact? Maybe you are just getting gravity flow.

EdTheHeaterMan

I might suggest an ECM pump with a small repipe to enhance air removal. The next thing is to make a map of each loop and determine what your required Head pressure PUMP HEAD is for the longest loop and what your GPM flow rate is if all zones are open.

diagram to follow

hot_rod

EdTheHeaterMan said:

I might suggest an ECM pump with a small repipe to enhance air removal. The next thing is to make a map of each loop and determine what your required Head pressure is for the longest loop and what your GPM flow rate is if all zones are open.

diagram to follow

You mean calculate the pressure drop in the various loops. There is no such thing as head pressure Just to be technically accurate.

https://www.pmengineer.com/articles/95823-john-siegenthaler-important-differences-between-head-and-delta-p

EdTheHeaterMan

hot_rod said:

You mean calculate the pressure drop in the various loops. There is no such thing as head pressure Just to be technically accurate.

I fixed it @hot_rod BOB!

EricJC

ok I will be going down to the house this weekend and will have to check more things out. I am not seeing any detectable flow on the returns of the manifold. Right now the only part of the loop we run the most is the living room and now not even that very much. We have Mr cool split mini units doing heating most of the time. The pump is humming away and runs alot. If it is degraded or not working properly is something I am uncertian of. I will probably try and replace the pump either way. for $359 for the Taco vt2218 i figure it is worth it. I was wondering if it wasn't pumping well and it was more gavity flow myself. I will replace the pump soon and let everyone know what happens.

EdTheHeaterMan

OK , here is the artwork.


Since this is an ongoing project, there is still old stuff and some new stuff on this manifold of zones.
To find the needed pump head go to the longest run (in my example it is 130 ft of PEX (65 ft each direction) then use the Rule of thumb from the Zoning Made Easy booklet. (page 7 for the zone and pages 10 to 11 for the shared piping)
130 (Actual Pex) x 1.33 (Shared Piping) x 1.5 (Total Equivalent Length) x .04 (4 feet of Head per 100 ft pipe) = 10.4 Pump Head

Then you need to calculate the total amount of heat for all the emitters operating at the same time. That would be 99,000 BTUh Your boiler is 93,000 NET, so that is probably good enough since it worked with the old pipes. That 93,000 converts to just under 9.5 GPM flow rate. So you need a pump that will develop 9.5 GPM at 10.4 Pump Head.

The ECM ∆P pump will regulate itself based on the 10.4 head and the number of open zone valves.

My guesses on your radiators are probably way high and you can most likely need only 80,000 or 75,000 BTUh which means that the pump will always pump less GPM than the maximum. Just select the pump based on the correct numbers and not by the SWAG (Seat of your pants Wild A?? Guess) method.

hot_rod

EricJC said:

ok I will be going down to the house this weekend and will have to check more things out. I am not seeing any detectable flow on the returns of the manifold. Right now the only part of the loop we run the most is the living room and now not even that very much. We have Mr cool split mini units doing heating most of the time. The pump is humming away and runs alot. If it is degraded or not working properly is something I am uncertian of. I will probably try and replace the pump either way. for $359 for the Taco vt2218 i figure it is worth it. I was wondering if it wasn't pumping well and it was more gavity flow myself. I will replace the pump soon and let everyone know what happens.

You want a delta P type of circulator. No need paying a lot for features you don’t need.

EdTheHeaterMan

The ∆T might be a good option. This way the pump will get to the minimum return water temperature faster and operate at that temperature longer. I just wonder if the Pump you selected is more than you need. You will never need 22 ft head or 18 GPM. The 007e will perform at 10 ft Head all the way to 9.5 GPM. That seems to be right in the example I offered. You will need to do your own math to see if you need more or less than 10 Ft Pump Head. @hot_rod BOB should chime in if I forgot anything or if Califfe has something to offer Like the Alpha Pump.

hot_rod

I've lost track of the Taco model numbers, use to be a VR delta P circ, maybe one of the new E pumps has multi speed, ∆P options. Doesn't matter which brand as long as it is sized correctly.

I think constrained ∆T operation is not a great match with that blend of high and low mass radiators. ODR confuses it even more.