Search results

By the way, I have downloaded that technical document and read portions of it probably at least 10 or more times in the last 4 years and I still didn't know for sure that the pump has an internal temperature sensor. This is what I'm talking about when I say that this stuff is very complicated.

Frodo, better sources such as the Caleffi videos previously mentioned will describe head loss/friction in better detail, but the way I think of it is: yes, you have to pump the water uphill, but you get all that energy back when it comes back down the hill, minus friction. Also, the vast...

Here is a fitting that could save some transitions and maybe connect directly to the vent.

Thank you chiming in, RenewDave. Do you think installing the vent at the elbow you mentioned is a better idea than, say, somewhere on the horizontal run in that same high region of the loop, maybe near the ball valve?

Correct me if I'm wrong, but I think the head loss calculation doesn't include the heights in a recirculation loop but only the lengths, fittings, pipe material and diameter. Without getting into all the nitty gritty, I will make the claim that both in theory and in practice, the head loss is...

Frodo, you may see this covered earlier in the thread: - The pump is a Grundfos #98420223, Model UP10-16 A PM BN5/LC I would be extremely grateful if anyone could find some details about the pump brain and sensors. How about start by explaining page 8 of the installation instructions: -...

The last time I purged the system, I closed the valve below the pump, and opened the hose bib and let a gallon or so of water out. That worked just fine and I've seen several days now of the system working fine. I'm trying to use some of the information I've gotten in this thread (thank you...

You're probably right that I am calling an aquastat (which is a temperature controlled switch) what is actually a temperature sensor. If only there were instructions with actual words that came with the pump I might have been more accurate. By the way, I am probably misusing the term...

Grundfos sensor location instructions

The pump does not have an internal check valve. Both of the check valves on the other side of the pump are spring type. However, as I understand it, the pump does not have to "work against cold water pushing back against hot water". If it did, I doubt the system would ever work. Remember that...

Frodo says, "aqua stat is closer than 5' from heater--false readings" This is a different subject, but one I've thought about quite a bit... Regarding the aqua stat, I think ideally it should be installed near the farthest fixture for a single loop system. This may require a different method...

Between Frodo and ExtraMilePlumbing, I'm considering the utility of a check valve after the pump. Can you explain why you think that will solve the problem?

"aqua stat is closer than 5' from heater--false readings" According to my reading of the pump instruction cartoon, the aqua stat must be placed 8-20 inches from the water heater. Where precisely do you suggest I put it if you think it's in the wrong place? "globe valves instead of ball valves"...

I really appreciate the input and will try to address some of the comments/suggestions. I was busy with my day job carpentering the last few days. I work on high end to uber high end homes and always make a point of checking out the mechanical room (AKA submarine). Some of the layouts I see...

Head vs. flow

Caleffi tank mixer with recirculation diagram

The thing is, something is causing the hot water to quit recirculating. I think it is air near the pump because, if I purge a bunch of water through the hose bib near the pump, the recirculation resumes. This happens every week or two, which is the point of the original post. I know that air...

EDIT: Come to think of it, I bet that loop on the discharge side of the pump could trap enough air to cause problems circulating. The top horizontal run of the loop is exactly where I thought the vent should go originally but the professional suggested otherwise. I don't fault him if he's...

I don't think any of this is relevant but will serve to explain the whole layout...There are 2 return lines because the heater is located roughly in the middle of the house so I have plumbed a 2 branch system. In fact only one branch is in use for now and the second is just a stub. The valve...

I'm not a plumber but I carefully installed a recirculation loop and pump and it doesn't leak. However, it didn't work either. I suspected the pump was air-locked, installed a hose bib near the pump to purge air. Success! But every week or two the system fails. I had assumed any air would...