In an attempt to set up my condensing boiler [WB Greenstar 24Si] to run at optimum flow temp, I'm looking for any recommendations for pipe thermometers. I have an LED point and shoot thermometer but it doesn't like measuring the temp of copper pipes and is significantly under recording.
There appears to be (as you would expect) quite a range of prices and I assume associated accurancy hence I'd appreciate any real life feedback on what to choose or avoid.
How about a pair of something like this:
Black tape on the pipe should help, I think.
The IR thermometers don't like reflective surfaces. Try wrapping black tape around your pipe and measuring that.
Also paint (of any colour) can work for 'black' here, which means you might have better luck on painted pipes.
Theo
Something I posted recently
Buy 4 off
Also order some replacement LR44 batteries (2 off per module) as the ones they come with may have been in there some time. Although these modules possibly may only have an accuracy to 2C select the two that give that best match and show the (near) same temperature. With a bit of luck all four will show the same temperature.
Tape one probe to the flow and another to the return pipes somewhere near the boiler. As the radiators are heating from cold you will first see a large difference in temperature but check when all the radiators that are turned on are hot and have been in that state for 15 minutes - and the boiler is still firing.
I've have two taped to my flow and return pipes near my boiler. The feed one reads the same as the digital reading on my boiler +/-2C.
I've experimented with reducing the flow temperature and where the outside temperature this year has been well below 10C I've found the best compromise to be a flow of 65C giving a return of around 12C lower when the system has reached temperature. However my boiler is possibly less than 2x oversize (maximum output) and my radiators possibly 40% oversized for a designed 70C flow.
If your boiler is oversized then you may not be able to get to a stage where it condensing and provide adequate heat. If you take the flow temperature down then you will have to increase your radiator sizes to compensate.
I've used these and while they're very convenient, I'm convinced they're reading rather low, though poor contact with the pipe. It's a shame they don't come with the correct curve associated with 22mm pipes.
As you have found, the point and shoot don't work too well with shiny surfaces, different surfaces may be giving you the temperature of something else being reflected, also different surfaces have a different emissivity and the cheaper point a shoot devices have no adjustment for this.
Something I posted recently
Buy 4 off
Also order some replacement LR44 batteries (2 off per module) as the ones they come with may have been in there some time. Although these modules possibly may only have an accuracy to 2C select the two that give that best match and show the (near) same temperature. With a bit of luck all four will show the same temperature.
Tape one probe to the flow and another to the return pipes somewhere near the boiler. As the radiators are heating from cold you will first see a large difference in temperature but check when all the radiators that are turned on are hot and have been in that state for 15 minutes - and the boiler is still firing.
/end
I've been experimenting with flow temperatures and the best compromised I've achieved is a 65C flow temperature with a resulting return approx
14C below this on a day when the outside temperature has been well below 10C. My boiler is probably less than x2 oversized (maximum output) and can modulate down by 3.8:1. My radiators were designed for a 70C flow but for when the heat loss of my house was around 30% more than now so currently they are slightly oversized.If your boiler is well oversized for heating then you may not achieve condensing operation. Also reducing the flow temperature may/will need the radiators being larger to compensate. A 1kW radiator designed for a flow temperature of 70C becomes a 0.5kW radiator when the flow is taken to 50C.
This may explain better
See corrected figures in another post - I accidently posted before I checked my records - although the above is indicative of what I've found on my system.
I did find that adjusting the flow to 60C (5C below what I now have set) was a stage too far in that it took longer to heat the house and possibly saved no money because the boiler was firing and using gas for much longer.
Many thanks for all the helpful feedback. I've ordered a set of LCD thermometers so will see how I get on. WB recommend 73C outbound temp assuming a 20C drop with a return temp of less than 52C.
I bought a pair of these, a few weeks ago and for that very purpose. They are not designed as pipe stats, but I would suggest they are even better, cheaper, much more accurate and easier to read.
To clip them onto pipes, just use a short bit of pipe insulation.
and some thermal interface compound between the pipe and sensor and some pipe insulation around both the sensor and pipe.
I think you meant 'undersized' there?
Oversized - it cannot modulate low enough and so is always providing too much heat whilst the burner is firing. It starts fast cycling on/off rather than just modulating down to match the building heat loss.
I have the same and found it's better to tape the sensor to the pipe with duct tape rather than just using the foam type pipe insulation.
I understand your point, but an undersized boiler struggling, will be working flat out at maximum output temperature, trying to meet the demand.
Tape, will mean that the sensor is surrounded by cooling air on most of its diameter, so it will under read the actual temperature. A short piece of pipe insulation will avoid that, as well as making the sensors clip on the pipes.
Having gradually increased my radiator sizes when redecorating, over a number of years, my Vaillant is running at 60°C outlet temperature - and so far perfectly satisfactorarily. It has only been a few weeks though, so I need some time yet to compare to previous years.
I am planning to modify things a bit though, so that I can use a higher temperature for the hot water cylinder - as currently there may not be enough hot water if we all have a shower one after the other. The cylinder being a little hotter would resolve that.
I have both. The sensors are taped to the pipes and the pipe run from my boiler, fitted in the old outside toilet, are foam insulated.
Some black PVC insulation tape on the pipe will give you are reasonably consistent point and shoot reading (and same on anything else).
Basically a metallic surface is a terrible radiator - a perfect mirror will reflect its environment back at your sensor. Any metallic surface is a very poor radiator and so fools a IR thermometer.
For the same reason medical non contact ones intended to measure human temperatures have to allow for the intrinsically not really a black body aspect of the emissivity of human skin and the flesh underneath it.
I tend to use the stick on LCD thermometers strips intended for electronics as essentially throw away items on boiler pipes and to check insulation. The ones for brewing work too and are cheaper on Amazon:
They last a good few years in situ. Longer in the dark.
That's the problem I have with my 1968 sized 30kW boiler. I've got the output temperature (according to the LEDs) set at 50deg and it still cycles. However I've only just put in a room thermostat so maybe it'll get round to modulating as the colder weather arrives.
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