Measuring the temp of copper pipes?

[DrFfybes]

Having had a new fangled condensing boiler, I am aware the alleged efficieny is better with lower flow temp, so about 50C.

However, there is the competing requirement to keep the cylinder above 60C to combat Legionella.

To get the cyl above 60C, the heating water reaching it needs to be higher, but how much higher? If the cyl is set to 60 wil heating it with water at 62 be OK, or does it need to be 65, or 68? And if the boiler is set to 65C, what is the temp of the water arriving at the cyl?

New pipework was run to the airing cupboard so I managed to partially insulate the existing pipes under the floor,so that will help.

Also if the water reaching the HWC is only a couple of degrees above the set temp, it will take longer to reach the set temp (if at all), so the boiler will run longer trying to hit the required temp, using more gas (or will it, as this one regulates the burn and the returning water will be hotter and require less heating).

So, what I want is a fairly accurate thermometer to measure the temp of the pipework as it reaches and leaves the boiler and the hot water pipe towards the shower. The infra red one I have is hopeless on shiny metal, so some sort of contact one would be best. It would also be good to be able to check the existing cyl stat is still vaguely accurate, as it has about 5C tolerance on the on/off.

Any suggestions for a suitable thermometer?

Paul

[DeepSporran]

Your infrared thermometer as you say will be hopeless on shiny metal - you can however wrap a bit of black electrical insulation tape round a shiny pipe and point the thermometer at that. The tape will be at the same temp as the underlying pipe and will give a good reading being a black matt(ish) surface. That’s what I do when balancing the system after fitting new valves etc.

[monabri]

If your boiler is in frequent use ( daily?) isn't the risk of Legionella v.low? I thought it only became an issue when water is stagnant in the pipes ( eg, a system left switched off for a long period).

[servodude]

Your infrared thermometer as you say will be hopeless on shiny metal - you can however wrap a bit of black electrical insulation tape round a shiny pipe and point the thermometer at that. The tape will be at the same temp as the underlying pipe and will give a good reading being a black matt(ish) surface. That’s what I do when balancing the system after fitting new valves etc.

Yup black PVC insulation tape works very well (having compared it with conductive thermometers for measuring the surface temp of shiny heating plates)

[BullDog]

If your boiler is in frequent use ( daily?) isn't the risk of Legionella v.low? I thought it only became an issue when water is stagnant in the pipes ( eg, a system left switched off for a long period).

But..... the main risk of legionella isn't in the hot water cylinder. It's in the shower head where the water sprays on to you. To contract legionnaires disease you have to breath in water droplets that are infected with the bacteria. I have to admit that when I use a hotel shower for the first time, I run the shower for a while at maximum temperature to try to mitigate the (low) risk of legionella. At home, I do periodically sanitise the shower heads. Perhaps not as often as I should, but I do. The thermostat on the hot water cylinder is set to 65 degrees C. The boiler thermostat is set to 70.

A similar hazard actually exists in car screen wash systems that are left to allow bacteria to accumulate. Using a commercial screen wash fluid is recommended because of that. Hope that helps.

[monabri]

If your boiler is in frequent use ( daily?) isn't the risk of Legionella v.low? I thought it only became an issue when water is stagnant in the pipes ( eg, a system left switched off for a long period).

But..... the main risk of legionella isn't in the hot water cylinder. It's in the shower head where the water sprays on to you. To contract legionnaires disease you have to breath in water droplets that are infected with the bacteria. I have to admit that when I use a hotel shower for the first time, I run the shower for a while at maximum temperature to try to mitigate the (low) risk of legionella. At home, I do periodically sanitise the shower heads. Perhaps not as often as I should, but I do. The thermostat on the hot water cylinder is set to 65 degrees C. The boiler thermostat is set to 70.

A similar hazard actually exists in car screen wash systems that are left to allow bacteria to accumulate. Using a commercial screen wash fluid is recommended because of that. Hope that helps.

Yes, true, regarding shower heads and I assume that DrFfybes and family use the shower on a regular basis

( as landlords we have to carry out a risk assessment for new tenants regarding Legionella and we also clean and sanitise the shower head with "Safe4" solution.)

[88V8]

Any suggestions for a suitable thermometer?

I think something like a pipe thermometer will do it.
https://www.ebay.co.uk/itm/265735052317 ... Sw5BJipwBa

V8

[Dod101]

If your boiler is in frequent use ( daily?) isn't the risk of Legionella v.low? I thought it only became an issue when water is stagnant in the pipes ( eg, a system left switched off for a long period).

But..... the main risk of legionella isn't in the hot water cylinder. It's in the shower head where the water sprays on to you. To contract legionnaires disease you have to breath in water droplets that are infected with the bacteria. I have to admit that when I use a hotel shower for the first time, I run the shower for a while at maximum temperature to try to mitigate the (low) risk of legionella. At home, I do periodically sanitise the shower heads. Perhaps not as often as I should, but I do. The thermostat on the hot water cylinder is set to 65 degrees C. The boiler thermostat is set to 70.

A similar hazard actually exists in car screen wash systems that are left to allow bacteria to accumulate. Using a commercial screen wash fluid is recommended because of that. Hope that helps.

Yes, true, regarding shower heads and I assume that DrFfybes and family use the shower on a regular basis

( as landlords we have to carry out a risk assessment for new tenants regarding Legionella and we also clean and sanitise the shower head with "Safe4" solution.)

I remove my showerhead from time to time, scrub it with the usual bathroom cleaner and then run very hot water through it. Does Safe4 do more than that? The reference I have seems to suggest that it is used for dogs?

Dod

[DrFfybes]

Thanks,

I'd heard about the tape idea, but tbh forgotten about it. I'll give it a whirl.

Re unused shower heads, certainly the guest en-suite only gets used for guests, which have been pretty rare the last couple of years. Hadn't really thought about that as we clean the 'main' one regularly due to limescale. Might remove the unused one and give it a bleach squirt.

Paul

[Neutrino]

I tried ‘pipe thermometers’ but found them inaccurate at measuring pipe temperatures because there is a large flat surface of the thermometer contacting the round surface of the pipe.

I fixed the sensors of aquarium tank thermometers to the boiler flow and return pipes with cable ties. A bit of heat sink grease can be added for good measure. Cover with some pipe insulation

It is not necessary to use black tape with an IR thermometer. Unless the item is red hot or white hot the radiant energy is not in the visible spectrum. White paint and white paper have good emissivity in the far infra-region to which an IR thermometer is sensitive. I stuck self adhesive white paper labels to the pipes.

Basic central heating controls only switch the boiler on or off. Better controls with compatible boilers will provide a fixed boiler flow temperature when the demand is for the hot water cylinder (~75°C) and modulate the boiler flow temperature when the demand is for heating (load compensation or weather compensation).

[DrFfybes]

I did a bit of experimenting..... the thermometer is one of these https://www.drapertools.com/product/151 ... ermometer/ or perhaps it's predecessor.

I rummaged in the tape drawer and found masking tape, some 'anti slip' tape from Aldi that is sticky backed 40 grit sandpaper (presumably inherited from the f-i-l about 6 years ago) and several different colours of insulating tape (I used red, white, and black).

First thing I realised is the laser indicator of where the IR thermometer is pointing is way off, it shows quite high, about 1/ inch out at 2 inch distance on a 22mm pipe. However all the tapes gave the same result, I just needed to hold the triger down on the thrmometer and swipe it back and forth slowly until the pipe was in the target area.

Second thing is with the boiler set at 68, outflow pipe read 67.2 within a minute of switching on. By the time I walked upstairs and measured it arriving at the HWC it read 67.7. Back to the boiler it was showing 69C on the readout, the pipe was 68C, so effectively no drop in temp from the boiler to the HWC, which is nice. The return pipe exting the post-bath HWC was 45C, and running the hot tap showed 42C exiting the HWC.

I'm on a roll now, there's bits of tape all over the place, under the sink, on the bath tap, so hours of fun next bath time

Paul

[staffordian]

Having had a new fangled condensing boiler, I am aware the alleged efficieny is better with lower flow temp, so about 50C.

Paul

As I understand it, the key requirement is to keep the return temperature rather than the flow temperature low, not sure if you are checking return and we are using different terminology, but if not, it does mean you don't need to worry quite so much about Legionella as the flow temperature can be higher than you are aiming for.

[Maroochydore]

My multi-meter has a separate probe for taking temperatures. It has a flat foot on the end to make a decent contact.

[csearle]

...and several different colours of insulating tape (I used red, white, and black)

For some reason I find blue, brown, and green/yellow to be in abundance. C.

[jfgw]

...and several different colours of insulating tape (I used red, white, and black)

For some reason I find blue, brown, and green/yellow to be in abundance. C.

I'm sure you have some black and grey to experiment with too.


Julian F. G. W.

[Mike4]

"Measuring the temp of copper pipes?"

Another approach is to grab the flow pipe with your hand and grip it tightly.

If you can hang onto it the temp is prolly less than 60C. If you are forced by reflex to let go of it either immediately or after five or ten seconds, it will be above 60C.

Hope that helps....

[DrFfybes]

"Measuring the temp of copper pipes?"

Another approach is to grab the flow pipe with your hand and grip it tightly.

If you can hang onto it the temp is prolly less than 60C. If you are forced by reflex to let go of it either immediately or after five or ten seconds, it will be above 60C.

Hope that helps....

Thanks Mike.

Having worked in labs for many years, I'd be very impressed if anyone could hold onto something at 60C for 10 seconds. The standard test for "is it cool enough to add the antibiotics to the gel media after autoclaving" was to see if you could comfortably hand hold it, in which case it was about 50C. Above that the antibiotics tended to be denatured when added, much below that and the media would solidify again as you poured it into the petri dishes.

Of course you could just allow the media to cool in a 45-50C water bath, but that took up resources and space, so generally someone would repurpose a 37C, then the heat made the post it note fall off, then someone else would use it thinking it was still set at 37, etc etc.

Paul

[Parky]

If your boiler is in frequent use ( daily?) isn't the risk of Legionella v.low? I thought it only became an issue when water is stagnant in the pipes ( eg, a system left switched off for a long period).

Is the Legionella risk relevant for closed pressurised HW systems? I thought it lurked in open topped cold water storage tanks.

[DrFfybes]

It got a bit odder. The pipe exiting the cylinder measured about 45C with the stat set to 60. This was disappointing. Turning the stat to 70 for the exit pipe up to 49C with the tap running. The good news is the bath tap read 50C so no heat loss once flowing.

I did wonder how the new boiler managed to heat the water and switch off in about 15 min. Turns out the plumber was testing the system and found the cyl wasn't calling for heat. Assuming we'd had the immersion on he turned the cyl stat to max to check the 3 way valve, and then turned it back to where he thought it should be. It seems to be 10-15C adrift, so time for a new one.

Paul