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Water Temp testing log

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Water Temp testing log

Post by spicknspan » Mon, 20th Mar 2017, 1:34pm

hi all.

I'm recently new to role of school caretaker, worked as a cleaner mostly for a while now just stepped up to the role of caretaker. Just getting my head around a few things now expected of me, been reading this site recently so thought a good place to ask a bit of advice. thanks in advance.

I will possibly get some training on this but like to get ahead start if possible. The water testing folder has a number of things I don't under stand such as flow return, flow temp, blended hot outlet temp and pre tmv hot temp? In terms of taking the temperature for those, how is that done? What do those mean?

thank s

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Re: Water Temp testing log

Post by xzimdave » Mon, 20th Mar 2017, 2:14pm

Hi spicknspan,

At our school these entries in the log are filled in by the company contracted by the school to deal with Statutory Monitoring for Legionella control.

However it's worth knowing what the various terms mean.

Depending on your school's water system lay out, there should be a hot water tank, called a calorifier, in the boiler room.
The flow temperature is the temp of the hot water leaving this tank, the return is the temp of water in the return pipe to the tank.
The blended hot outlet temp is the temp of the water leaving a basin tap, and the pre Thermostatic Mixing Valve temp is the temp of the water before it enters the TMV. These temperatures are measured by a probe held against the pipe work or in the flow from a tap.

Hope that helps a bit

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Re: Water Temp testing log

Post by HappyLad » Mon, 20th Mar 2017, 2:22pm

Flow/return is the water temperature that leaves your water calorifier (hot tank). Basically water needs to be stored at a temperature that won't allow the harboring of legionella.

Have a look at this: ... endix3.htm

TMV's are thermostatic mixer valves, they blend the hot & cold water at an outlet to produce a temperature between 39 & 43. This is to avoid scolding. You need to test these taps at defined intervals, but you also need to test the water in the pipe just prior to the mixer valve to ensure it's being delivered at a high enough temperature to ward off the bacteria.

You'll need to buy a temperature testing machine if you don't have one, mine has 2 different probes, one for running water and one for measuring a pipe temperature. Something like this: ... rated.html
Shop around, as ever prices vary and you may need less or more level of sophistication.

Good luck, just be thorough but it isn't rocket science.
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Re: Water Temp testing log

Post by seanallen » Tue, 21st Mar 2017, 4:59pm

Does your boiler room have a Trend control system? (it will have a grey LCD screen on the boiler control panel) If so the flow and return temps should be logged automatically. If you have your heating engineer or county surveyor should be able to show you how to retrieve the information you need.
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