Circ. Pump on Supply or Return?

Brian_7

Hi Mark - (or any of the other knowledgeable ones here)- I have a Q. about your diagramme, or more generally about system design. I notice that one pump sized large enough to service the entire system when all zone valves are open would be used. If only one zone is calling for heat then the pump would be putting out much more than necessary for that one zone. Would it not be a good design to replace each of the zone valves with a small pump, and eliminate the larger pump all together? Then each pump would be sized for the zone it services. (Uses only enough electricity as is required). Also, the failure of one pump would not be as catastrophic in winter when the owner is away on vacation, as would be the case if one larger pump were to fail.
I'm an industrial designer and know little about HVAC and RFH, but my house is presently being constructed with a system which was designed with one large pump and zone valves, and I'm not sure why they seem to be done that way. I can't see there being much cost difference, or is there? What am I missing here?
Thanks - Brian.

Chris Clark

Circ. Pump on supply or return

I have been in the field since 85', mostly residential warm air systems, but getting more into the wet stuff. I'd like to get some opinions on a three zone valve, single circ. hot water application, Weil McClain Gold, Oil. If anyone has example drawings on piping for this example, circ. on supply or return?, which is best, also example of location of PRV/Backflow,Tank,Scoop,vents,etc.
Thanks, I respect the opinions of experts in this forum!
Chris Clark, Owner, Chris Clark HVAC

[Deleted User]

Pump away!!!

Hiya Chris, Welcome to The Wall. To your left you will see a button marked Books and More. Grab your credit card and get ready to get edumucated.

First, get the book titled "Pumping Away". Thats a good primer for someone whos been "doing it" for as long as you have. It will answer many of your questions.

While you're there, check out Ellen Rohrs books, "How Much should I charge", and "Where DID the money go?" Both excellent books even for an old salt like yourself.

As for prefered pump location, the manufacturers ship the boiler with the pump mounted to the return for one reason. Convenience. It's easier than having to ship the pump in a separate box, or have it rolling around loose inside the boiler, breaking of ignitors and what not.

I used to put my pumps on the return because the ol' boy that taught me told me that that was where the coolest water was, and it would extend the life expectancy of the seals and motor of my pump. BUNK!

The seals on todays pumps (those that still have mechanical seals) are rated for temepratures MUCH higher than a typical system operates at today, and the motors are also made to operate continuously at temps much higher than they typically do. I see my old mentor every now and again, and I've finally convinced him to do it the right way. He tells me that his fall start up complaints have dwindled to nothing on the systems hes set up as pumping away...

Will the system work with the pump in the less than ideal position? Obvioulsy it will. If the pump is in the right position, it will work a LOT better. Trsut us, if you try it, you'll like it and you won't go back. There's no reason to go back.

Here's a drawing of an ideal system configuration.

Tell us a little about yourself. How'd you find our secret hiding place:-)

Again, welcome to the wall and remember, there's no such thing as a stupid question, just stupid mistakes made by people that were afraid to look stupid by asking a question that twenty other people also wanted to ask. Ask away!!

ME

[Deleted User]

Pump away!!!

Hiya Chris, Welcome to The Wall. To your left you will see a button marked Books and More. Grab your credit card and get ready to get edumucated.

First, get the book titled "Pumping Away". Thats a good primer for someone whos been "doing it" for as long as you have. It will answer many of your questions.

While you're there, check out Ellen Rohrs books, "How Much should I charge", and "Where DID the money go?" Both excellent books even for an old salt like yourself.

As for prefered pump location, the manufacturers ship the boiler with the pump mounted to the return for one reason. Convenience. It's easier than having to ship the pump in a separate box, or have it rolling around loose inside the boiler, breaking of ignitors and what not.

I used to put my pumps on the return because the ol' boy that taught me told me that that was where the coolest water was, and it would extend the life expectancy of the seals and motor of my pump. BUNK!

The seals on todays pumps (those that still have mechanical seals) are rated for temepratures MUCH higher than a typical system operates at today, and the motors are also made to operate continuously at temps much higher than they typically do. I see my old mentor every now and again, and I've finally convinced him to do it the right way. He tells me that his fall start up complaints have dwindled to nothing on the systems hes set up as pumping away...

Will the system work with the pump in the less than ideal position? Obvioulsy it will. If the pump is in the right position, it will work a LOT better. Trsut us, if you try it, you'll like it and you won't go back. There's no reason to go back.

Here's a drawing of an ideal system configuration.

Tell us a little about yourself. How'd you find our secret hiding place:-)

Again, welcome to the wall and remember, there's no such thing as a stupid question, just stupid mistakes made by people that were afraid to look stupid by asking a question that twenty other people also wanted to ask. Ask away!!

ME

[Deleted User]

Pump away!!!

Hiya Chris, Welcome to The Wall. To your left you will see a button marked Books and More. Grab your credit card and get ready to get edumucated.

First, get the book titled "Pumping Away". Thats a good primer for someone whos been "doing it" for as long as you have. It will answer many of your questions.

While you're there, check out Ellen Rohrs books, "How Much should I charge", and "Where DID the money go?" Both excellent books even for an old salt like yourself.

As for prefered pump location, the manufacturers ship the boiler with the pump mounted to the return for one reason. Convenience. It's easier than having to ship the pump in a separate box, or have it rolling around loose inside the boiler, breaking of ignitors and what not.

I used to put my pumps on the return because the ol' boy that taught me told me that that was where the coolest water was, and it would extend the life expectancy of the seals and motor of my pump. BUNK!

The seals on todays pumps (those that still have mechanical seals) are rated for temepratures MUCH higher than a typical system operates at today, and the motors are also made to operate continuously at temps much higher than they typically do. I see my old mentor every now and again, and I've finally convinced him to do it the right way. He tells me that his fall start up complaints have dwindled to nothing on the systems hes set up as pumping away...

Will the system work with the pump in the less than ideal position? Obvioulsy it will. If the pump is in the right position, it will work a LOT better. Trsut us, if you try it, you'll like it and you won't go back. There's no reason to go back.

Here's a drawing of an ideal system configuration.

Tell us a little about yourself. How'd you find our secret hiding place:-)

Again, welcome to the wall and remember, there's no such thing as a stupid question, just stupid mistakes made by people that were afraid to look stupid by asking a question that twenty other people also wanted to ask. Ask away!!

ME

Chris Clark

Mark,
Thanks for the valuable info, explained in layman's terms. I hope all is going well with you and your career.

Floyd

Here's a couple of pics...

not single pump though... the first is actually pumping away, even though the pump is closer to the return....it is still pumping away from the PONPC and the piping on the primary loop is so short that it works great and assures that there is a positve flow to temper the cold water from the radiant slab if that is the only zone running.

The other pic. is hard to see... but each zone has it's own pump and is pumping away.