Installed new circulator

ALH_4

You can close the valve on the discharge a little to throttle the pump. If they are ball valves, the first quarter turn or so has little effect on the head loss, particularly at low flow rates. You might stand there on a sunny day and close it a little at a time until you get the supply temp you want. Static pressure will not affect the flow rate. Do you have a flow meter on the system?

cheftim

Installed new circulator

The circulator in my 3 panel closed loop solar DHW system failed. It was a 20yo Grundfos 3 speed. I replaced it with a new 15-15 Grundfos 3 speed. Even on the lowest setting, I'm barely seeing temps of 120 coming from the panel on a sunny day. I used to see 150. I think the speed is too high.

Does increasing the system pressure affect the fluid flow?

Any thoughts on how to slow the flow down? I have two ball valves before and after the pump. Maybe close them down a bit?

Rodney Summers

Can't find one

I don't have a flow meter. I'd like to find one if possible but all I ever come up with on searches is a flow control for a shower. Can you specify a brand or model? I could use a couple of those.

I'm going to try the 'watch it on a sunny day and close the valve' approach when we see the sun again.

Thanks

ALH_4

Rotometers

I like the Pentair Rotometers for use as solar flowmeters. There is a good selection of flow ranges. You can buy them online from King Solar if you don't have a local Pentair distributor.

I also like the Pentair Inline Thermometers. They are also available online from King Solar if you don't have a local Pentair distributor.

There is a lot of valuable solar design information in this document.