In-line sparge heater (or not)

[The-Engineer-That-Brews]

A slightly irritating feature of my setup is not having a separate sparge heater.
It‘s not a problem because I sparge from the Burco. But it does mean I have to collect the wort in a separate bucket so I can’t easily start heating for the boil until after the sparge.

So I was idly wonder whether I could free up the Burco by heating the sparge water ‘in-line’ using my HERMS setup instead, which uses a separate kettle.

I did a few calculations and the results surprised me.

• Running one of my little pumps through the counterflow and the sparge arm (which is what I do while recirculating) gives me a flow rate of 1.9 litres/min = 31.7 ml/sec.
• Let’s say I want to raise the sparge water from 12°c to 75°c: a difference of 63 degrees.

The heat capacity of water is about 4200 Joules/kg/degree, so the energy needed to raise 31.7 ml of water by 63°c is a surprisingly high 8,400 Joules. Doing so every second would therefore require an 8.4kW heater: getting on for three times the power of a domestic kettle (!)

I guess that’s why those ‘on demand’ showers you get in budget hotels tend to be a bit weedy.

However I don’t think the idea is entirely dead in the water. In reality a flow rate of 1.9 litres per minute is too high. At that speed it would go through a typical 16 litre sparge volume in only 8-9 mins, whereas I’d always aim for 20-30 mins spargeing. Granted, the sparge water is probably only running in for about 2/3rds of that time - but we are getting closer to the ballpark here.
The other factor is the starting water temperature. Pre-heating the sparge water in the Burco to something like 40°c during the mash, and then dumping it into a separate bucket to free up the kettle for wort collection would definitely put the required temperature increase within ‘HERMS’ range.

Plenty to think about here…

 

[The-Engineer-That-Brews]

Of course, I could get a separate sparge heater. But where’s the fun in that?

 

[Agentgonzo]

3 kettles?

 

[Agentgonzo]

But also, sparge water isn't as important to get up to the correct temperature as other things. You can sparge with cooler, or even cold water. All the sugar is already in solution anyway.

I've never needed to try it out, but it would be interesting to compare the gravity of wort collected with standard sparging and with cold (or luke-warm) sparging

 

[Hazelwood Brewery]

I used to sparge with cold water and it made little difference to efficiency. A small downside maybe is that you cool your wort prior to the boil. A small advantage for me was that it cooled the grain so I could handle it sooner for cleaning up.

As @Agentgonzo noted the sparge water temperature isn’t that important (up to mash-out temps) so don’t fret too much about heating to a specific temperature. If you have a really thick mash I can see the benefit in a warmer temperature for washing off the sticky sugars but 70 degrees is probably no better than 40 degrees for practical purposes.

These days I heat the sparge water on the hob during the last few minutes of the mash. My sparge water is usually in the range 60-65C.

 

[The-Engineer-That-Brews]

3 kettles?

The idea had occurred... that'd be entertaining, but a no-no from the electrical supply PoV :-)

 

[Buffers brewery]

You could slow your flow rate down. When I used 12 volt d.c. solar pumps I throttled them back using a model railway controller. Or you could just put a tap on the outflow side of the pump. I don’t sparge as such but do three mashes, recirculating the second and third mashes for 15 minutes. Like you, I store the wort from the first and second mashes in an empty fermentation bucket. Then during the third mash having emptied the kettle I transfer the wort from the bucket to the kettle and start the boil. The last mash gets added just as the kettle’s coming to the boil.

 

[DocAnna]

How about one of these...?
https://www.amazon.co.uk/Instant-Showers-Tankless-Electric-Efficient/dp/B09V7CV3J3/
Or even cheaper
https://www.amazon.co.uk/Queiting-Electric-Digital-Display-Bathroom/dp/B08L6GL9TD/

 

[The-Engineer-That-Brews]

I used to sparge with cold water and it made little difference to efficiency. A small downside maybe is that you cool your wort prior to the boil. A small advantage for me was that it cooled the grain so I could handle it sooner for cleaning up.

As @Agentgonzo noted the sparge water temperature isn’t that important (up to mash-out temps) so don’t fret too much about heating to a specific temperature. If you have a really thick mash I can see the benefit in a warmer temperature for washing off the sticky sugars but 70 degrees is probably no better than 40 degrees for practical purposes.

These days I heat the sparge water on the hob during the last few minutes of the mash. My sparge water is usually in the range 60-65C.

Very very interesting - thanks both. I've never thought of sparging with anything but hot water and it seems like heresy: but as you say, the consensus seems to be that it works fine (some say it drops the OG by a couple of points). I’ve always been fairly careful with the sparge temp because of the scare stories about tannin extraction but it sounds more like that’s a case of avoiding going over temp?

 

[Hazelwood Brewery]

Very very interesting - thanks both. I've never thought of sparging with anything but hot water and it seems like heresy: but as you say, the consensus seems to be that it works fine (some say it drops the OG by a couple of points). I’ve always been fairly careful with the sparge temp because of the scare stories about tannin extraction but it sounds more like that’s a case of avoiding going over temp?

Yes that’s right, sparge temperatures over about 77C, sparge water pH over 6.0, and runnings below 1.010 (at the end of the fly sparge) are all supposed to make extraction of bitter tannins from the grain husks more likely - but not assured I think. Not that I’d suggest ignoring these.

 

[Bzee]

I do a single batch sparge and before I open the tap on my mash tun I put my boiler/saucepan on the floor to collect the wort. Can't fit two vessels on my hob anyways but I am cooking on gas.