Little Brown Pump not enough power

Aussie Home Brewer

Help Support Aussie Home Brewer:

iralosavic

Well-Known Member
Joined
17/10/11
Messages
1,131
Reaction score
21
My hot water test run went fine on my 2 tier 3v+HX HERMS system, my actual brew day did not.

The plan was to change the outlet from the HX from the MLT input to just hanging over the side of the boiler (until I get the appropriate fitting to allow underletting), however, the LBP did just not have the guts to pump that far, which is interesting, as it manages quite fine to the MLT return and the boiler is only another 15cm higher (due to the burner platform).

Obviously I could possibly solve this by instead redirecting the flow from the pump outlet and not involve the HX at all, but I was a little suprirsed/disappointed by this and it did mean I had to batch sparge to a pot on the ground and lift it to tip into the boiler 6 or so times, which was a bit risky and a PITA.

Also i swear I heard the pump stop operating for a while when flow had slowed down or stopped (it was definitely still primed [liquid full on in and out hoses]).

I'm not too fussed as I have a Chugger on the way, but I thought I'd post in case there's somthing I've missed.

Cheers
 

Yob

Hop to it
Joined
14/11/09
Messages
15,036
Reaction score
6,410
Location
Ringwood, Melbourne
how long are your hoses that it has to pump? the 12v models have a 3m Head and the 24V have a 5m head, the shorter your hoses the better.
 

robbo5253

Well-Known Member
Joined
12/1/06
Messages
361
Reaction score
20
Could you fill your kettle through the Tap?
 

iralosavic

Well-Known Member
Joined
17/10/11
Messages
1,131
Reaction score
21
Yob said:
how long are your hoses that it has to pump? the 12v models have a 3m Head and the 24V have a 5m head, the shorter your hoses the better.
Well I'm not sure how long the HX coil is, but the hose from pump outlet to hx is about 40cm and the hose from the HX outlet is quite long (so it can reach the boiler) - I'd estimate around 100-120cm. I couldn't really get away with reducing the length in its current setup (ie passing through the HX) or else it wouldn't reach the boiler, however I do plan on setting up a 3way valve at the outlet and having a dedicated hose for transferring wort from MLT to Boiler and this brings me to my answer for robbo;

robbo5253 said:
Could you fill your kettle through the Tap?
I am waiting on a fitting to put on the boiler tap so that my hose fitting is compatible so that I can do just this (underlet). Meanwhile I'm limited to putting the hose over the side.
 

Adr_0

Gear Bod
Joined
4/4/13
Messages
1,776
Reaction score
684
how big are your hoses, and what about the internal diameter of your HX? What is your height from the centre of the inlet to the highest point on the tubing?

This pump will flow a max of about 7lpm just pumping out against 5-10cm (at a guess) i.e. enough to keep the impeller full of water. 3-3m of head will be at 0lpm, i.e. definitely not 7lpm. If you are taking away 0.5-2m or so in static head that it has to pump against, you are immediately reducing its max flow even if you have 3/4" tubing pumping straight there.

if you have a few metres of copper tube it's not too bad (e.g. 3m of normal wall thickness 1/2" tube should lose you about 0.5m at 3-4lpm) but if you have quite a bit of copper tube - or 3/8" for e.g. - in a HX you are losing quite a bit more. your 7lpm pump will suddently be trickling out 2lpm or less, which is going to have you looking at your watch a lot.
 

iralosavic

Well-Known Member
Joined
17/10/11
Messages
1,131
Reaction score
21
Nev, why wouldn't I be? It's powered by the HERMIT controller. I don't have a current meter to test it with.
 

iralosavic

Well-Known Member
Joined
17/10/11
Messages
1,131
Reaction score
21
Adr_0 said:
how big are your hoses, and what about the internal diameter of your HX? What is your height from the centre of the inlet to the highest point on the tubing?

This pump will flow a max of about 7lpm just pumping out against 5-10cm (at a guess) i.e. enough to keep the impeller full of water. 3-3m of head will be at 0lpm, i.e. definitely not 7lpm. If you are taking away 0.5-2m or so in static head that it has to pump against, you are immediately reducing its max flow even if you have 3/4" tubing pumping straight there.

if you have a few metres of copper tube it's not too bad (e.g. 3m of normal wall thickness 1/2" tube should lose you about 0.5m at 3-4lpm) but if you have quite a bit of copper tube - or 3/8" for e.g. - in a HX you are losing quite a bit more. your 7lpm pump will suddently be trickling out 2lpm or less, which is going to have you looking at your watch a lot.
Thanks for the info. When looking at it like that, it makes sense, but the confusing thing is that it pumps with plenty of pressure when connected to the MLT input, but not at all when I move the same hose a metre to the side and up by 15cm. I guess it just runs out of oomph.
 

iralosavic

Well-Known Member
Joined
17/10/11
Messages
1,131
Reaction score
21
Gryphon Brewing said:
If you have long leads it may suck power.
Nev
Ah ok, well that may be the case, but I don't have a meter. I could just cut the length back and see
 

Adr_0

Gear Bod
Joined
4/4/13
Messages
1,776
Reaction score
684
iralosavic said:
Thanks for the info. When looking at it like that, it makes sense, but the confusing thing is that it pumps with plenty of pressure when connected to the MLT input, but not at all when I move the same hose a metre to the side and up by 15cm. I guess it just runs out of oomph.
While static head (height of liquid pumping against) is one thing, what about frictional loss in pipe? The 15cm may not be much but how much pipe is in your HX and what is the diameter of the tube inside? Or, what is the design of the HX?
 

iralosavic

Well-Known Member
Joined
17/10/11
Messages
1,131
Reaction score
21
Adr_0 said:
While static head (height of liquid pumping against) is one thing, what about frictional loss in pipe? The 15cm may not be much but how much pipe is in your HX and what is the diameter of the tube inside? Or, what is the design of the HX?
Nev can probably answer that as I bought the whole setup from him including the heavy duty silicone hose that I'm using at all connections. I assume the hose is 1/2" ID and the HX looks like 10mm or so. I have no idea on the length of the HX coil though.
 

Adr_0

Gear Bod
Joined
4/4/13
Messages
1,776
Reaction score
684
Just a quick comparison doing some flow calcs:
1.2m of 1/2" tube should get you pretty close to 7L/m
1.2m of 1/2" tube + 1m of 3/8" tube + 15cm extra head = 5L/m
1.2m of 1/2" tube + 1.5m 3/8" tube + 15cm extra head = 4L/m

So it's quite sensitive to 3/8"/10mm tube if you do have that in your HX.

I have a graph/spreadsheet and may upload tonight but not at the moment.

EDIT:
No edit, but will just add that the the "1.2" tube only" cases assume it's pumping dead level, i.e. not even 0.5m to the top of a HLT. You will need to measure the distance from the centreline of the inlet (the nozzle in the middle of the Brown pump) to the highest level in the MLT if you fill from the bottom, or to the top of the MLT if you go in over the top. But it gives you a good idea of the impact of 3/8" tube on this pump.
 

Online Brewing Supplies

**** OBS ****
Joined
17/5/06
Messages
4,739
Reaction score
639
Location
The Dean WA
iralosavic said:
Nev can probably answer that as I bought the whole setup from him including the heavy duty silicone hose that I'm using at all connections. I assume the hose is 1/2" ID and the HX looks like 10mm or so. I have no idea on the length of the HX coil though.
12mm OD, 10mmID, not sure on the length with out calculating, but factor in 2m approx.
Nev
 

Adr_0

Gear Bod
Joined
4/4/13
Messages
1,776
Reaction score
684
Hey guys,
See the attached, rough expected flows from the Brown pump with different copper tube sizes. I have taken a guess at the actual curve, but don't think it will be flatter than this as a flatter curve is only really seen on much larger frame pumps.

But from it, you can see the following:
- Where the pump curve meets the 'system' curve (i.e. 2m of tube) is approximately where the flow should be
- reducing speed or power will move the pump curve down and to the left and you will have less potential head and flow
- reducing internal diameter (e.g. 1/2" down to 3/8") will drastically 'steepen' the system curve and you will lose flow
- adding length will do the same thing, but not nearly as dramatically
- adding height to pump against will shift the system curve up, so you lose flow

Not claiming the numbers are 100% but they are probably not very far off. More important is the concepts.

So... start with the wires (power) and then look at how much tube/hose the system is pumping against, and consider if you can slightly lower the MLT.

Good luck...

Adrian

EDIT: The above curves assume you are pumping over the top of a 350mm MLT.
 

Truman42

Well-Known Member
Joined
31/7/11
Messages
3,966
Reaction score
605
Mate my setup is very similar to yours (as you know). I have my MLT out hose down through my hex coil then out to my brown pump. So far to get to the pump gravity has done all the work. The pump then pushes the wort up about 750 mm to the mash tun inlet. When transferring to kettle I switch a 3 way valve which then pumps even further to the top and over the side of my kettle.

So if your pump is before your hex switch it to after your hex. here is a photo of how mine is setup.
 

Truman42

Well-Known Member
Joined
31/7/11
Messages
3,966
Reaction score
605
Mate my setup is very similar to yours as you know). I have my MLT out hose down through my hex coil then out to my brown pump. So far to get to the pump gravity has done all the work. The pump then pushes the wort up about 750 mm to the mash tun inlet. When transferring to kettle I switch a 3 way valve which then pumps even further to the top and over the side of my kettle.

So if your pump is before your hex switch it to after your hex. here is a photo of how mine is setup.
 

Truman42

Well-Known Member
Joined
31/7/11
Messages
3,966
Reaction score
605
Sorry about the double post, and I cant seem to upload the file. AHB is having problems it seems.
 

Latest posts

Top