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How to pre-heat water for HMA - article by Brent Sapsed.


A recent trend with HMA filters has been to rig them up to a warm water source so as to add large amounts of filtered water directly to your tank. Here at DD will still use cold water as our systems are drip fed 24/7 - however a long term customer of ours, Brent Sapsed, has written this article to explain how he has achieved pre-heating his water change water to 30-C using a domestic combination boiler, a mains cold supply, a TMV, some additional pipework and John Guest fittings.

Please note,

1/ The water flowing through the filter must never exceed the maximum temperature advised by the manufacturer. Keeping at 28 to 30 degrees C makes perfect sense especially if adding to an aquarium housing fish etc

2/ 3/8" or 1/2" John Guest fittings and tube is recommended, likewise 20" housings, otherwise you may not get the flow to ignite the boiler - consult your boiler manual for minimum flow requirements.

3/ We cannot give any technical advice for hooking a HMA up a boiler - be aware that doing so may invalidate any warranty - you must contact a qualified heating engineer if unsure.

Brent's article - part one

Brent's article - part one

You will need a good quality TMV. I use a Pegler Yorkshire 15mm TMV 2/3.

Buy these from plumbers merchants, Screwfix Direct etc.

Step two

Step two

I connect to the hot supply via a washing machine tap (most homes have one fitted but not used because most washing machines only use cold feed).

I use a washing machine "Y" piece to split the cold supply so I can connect TMV and washing machine to same washing machine tap.

Step three

Step three

I use a hot and cold washing machine hose to connect hot and cold feeds to TMV , If you unscrew the two large nuts on the sides of the TMV the threads that are on the TMV are 3/4" so you can screw the washing machine hoses straight on (I add PTFE tape to the threads).

Step four

Step four

I then take the nut off the bottom of TMV leaving a 1/2" thread , I screw on a 1/2" bsp female to 3/8" PF so I can connect onto my 20" HMA filter using 3/8" pipe.

**The JG fittings are avaiable in 1/2" + 3/4" bsp click here...

Setting the temperature

To set the temp I turn the TMV down as cold as it will go and adjust the temp up slowly until I get to desired temp. For me its 29 Deg C.
I can then run the water direct into tank from HMA filter up to 7.6 Lpm at the correct temperature. This has saved me time and money, Time because I don't need to wait for a barrel of stored water to heat up and no barrel to clean every few weeks and money because heating with gas is so much cheaper than electric.

Brent's installed HMA

Brent's installed HMA

This is a picture of my DD HMA 200 under kitchen units.(bracket removed)

I bought my 20" HMA filter , Cartridges , pipe and fittings from Devotedly Discus

DD range of HMA filters suitable for pre-heated water