Ok, first off, I'm swedish *bork bork bork*, so excuse me if my wording is a bit strange. Also I don't really know standard pipe sizes in the US, but I think at least you'll know what I'm getting at and could adapt.
Ok, so I'm doing 6-7 gallon (that is 23-27 liters approx) batches, I fly sparge as most all grainers do here (except biab brewers). During mashing I recirculate for half an hour or so, using a solarprojects pump (you know the cheap, small, but foodgrade 12v kind). I set the flow using a LED dimmer to pretty much as little a possible to avoid compacting the grainbed.
However, during recirculation, temperature drops typically 10F (5C). So, I was thinking about building a RIMS heater. I've seen the stuff put up here, and although very cool, way überkill for my budget and needs. But I've taken one thing away from these threads. Cleanability.
So, I want a cheap, easily cleaned, lower power heater, and this is what I came up with.
I bought a cheap stainless steel cartridge heater off ebay, 300mm length, 10mm dia and 600 w power. I used a 22mm copper pipe, cut to be just a bit longer than the heater. Drilled holes for hose connections, and soldered in 10mm pipes. The silicone hose from the pump can be attached with mild force.
The heater is held in place and sealed using silicone bungs (inteded for airlocks).
Here's a pic of it all assembled.
So far I have only tested with water, but it works. And yeah, I know about electrical safety, it will be grounded and ground fault protected.