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I bought one of these commonly used pumps second hand from a fellow brewer less than a month ago, hooked it up this weekend with some fittings, silicone to push mash liquor through a stainless HE coil back up to the same mash tun. To my surprise, the setup was unable to even circulate water, so I aborted the idea of enjoying a HERMS system and went back to manual mashing.
I primed the pump by filling the Mash tun with hot water which fed the pump through my false bottom. The only thing to note is that the silicone is 1/2" internal diameter but there is a short hose which has an outer diameter that fits inside the silicone hose so the water supply would be a bit less than full 1/2" bore.
I had hoped that by using gravity from the mash tun, the water would already have a bit of pressure behind it so the pump could achieve the desired result. During my test, I needed the pump to push the water through 7 meters of fairly thick coiled stainless pipe (not the jockey box thin stuff - about the standard diameter for copper piping) and then up for about 80 cm. The water ever only made it about 20 cm past the top of the coil before it just lingered there.
I even raised the pump about 50cm higher (making sure there was more than enough water in the pipework) and it still couldn't get over beyond the original mark.
I haven't read anything which indicates that these pumps are so low powered. From what I read, they can generate enough pressure to overcome 2.5m of vertical rises so while there is resistance in the stainless coil, there was only 80cm of a vertical rise.
Does anyone have any suggestions?
Here is a (rather dodgy) drawing to show what the setup is like.
As I mentioned, hose is going from smaller diameter exiting the mash tun to the pump.
Pump has valve on it in case I need to slow it down in the future (yes, I did check that one and it was on open)
There is about a 15-20cm rise to get to the HE coil
Coil is about 7 meters and has similar / identical internal diameter to 1/2" copper pipe
From the HE coil exit, it is about 80cm to get to the top of the Mash tun.
I primed the pump by filling the Mash tun with hot water which fed the pump through my false bottom. The only thing to note is that the silicone is 1/2" internal diameter but there is a short hose which has an outer diameter that fits inside the silicone hose so the water supply would be a bit less than full 1/2" bore.
I had hoped that by using gravity from the mash tun, the water would already have a bit of pressure behind it so the pump could achieve the desired result. During my test, I needed the pump to push the water through 7 meters of fairly thick coiled stainless pipe (not the jockey box thin stuff - about the standard diameter for copper piping) and then up for about 80 cm. The water ever only made it about 20 cm past the top of the coil before it just lingered there.
I even raised the pump about 50cm higher (making sure there was more than enough water in the pipework) and it still couldn't get over beyond the original mark.
I haven't read anything which indicates that these pumps are so low powered. From what I read, they can generate enough pressure to overcome 2.5m of vertical rises so while there is resistance in the stainless coil, there was only 80cm of a vertical rise.
Does anyone have any suggestions?
Here is a (rather dodgy) drawing to show what the setup is like.
As I mentioned, hose is going from smaller diameter exiting the mash tun to the pump.
Pump has valve on it in case I need to slow it down in the future (yes, I did check that one and it was on open)
There is about a 15-20cm rise to get to the HE coil
Coil is about 7 meters and has similar / identical internal diameter to 1/2" copper pipe
From the HE coil exit, it is about 80cm to get to the top of the Mash tun.