A problem or not a problem?

[MikeGrahamT21]

Hi

 

This has been bugging me for a while, but I’m still not sure if anything is wrong as I’ve nothing really to compare it to, but one thing stands out as odd, and defying physics.

 

So MVHR system has been in around 4 years now, set the valves up last year. Unit is a Vortice HR200BP serving a small 79m2 bungalow, with all of the radial ducting in the loft under heaps of insulation. The inlet and exhaust ducts are preformed polystyrene type with a small amount of flexible ducting where needed, so as to create as little pressure drop as possible, and there is also a Blauberg Cleanbox 125 on the inlet, with G4, H16 and Carbon filtration in there.

 

Couple of years back i bought some cheap temperature sensors off amazon just out of curiousity, as although the unit has its own temperature readings, they don’t include the temperature going back into the property, only extract, inlet and exhaust.

 

Now I’m sure for a long time everything seemed feasible temperature wise, the extract was around the temperature of the bungalow, and the supply was slightly lower as you’d expect, some small losses.

 

 

Now it’s constantly higher than the extract, which is obviously not possible, there is no magic heater or anything in the ducting. You’re probably thinking, just cheap sensors that aren’t reading right, i thought so too, so i swapped the supply and extract ones round and the ‘bad’ reading followed (and yes I relocated them on the wall correctly too! lol).

 

Yesterday I had the unit all apart and checked everything, cleaned the G3 filter which is has on its extract side, and washed the heat exchanger out (though to be honest, aside from dust on the filter, it all looks like brand new in there), and it this point i moved the sensor which I had on the intake, to the exhaust just to see what temperature it showed compared with the units own sensors, and I was surprised to see it showing 17C, with an outside temp of 9C currently.

 

 

Now the units own sensors shows 14C as the exhaust temp, and the sensors are literally next to each other, but could just be the poor quality sensors again?

 

My main concern is the fact the supply seems to be warmer than the extract?! The air coming out of the ceiling valves using an IR thermometer shows between 18.8 and 19.5C depending on how far the pipe run is, which seems feasible.

 

Does this all look OK compared with your units?

 

Thanks in advance!

[JohnMo]

Dodgy temperature reading to me, or you have the wrong identity assigned to each gauge?

 

So rubbish in, rubbish out. You seem to making an issue from reading from a £1 gauge.

[Nickfromwales]

Internal pre/post heater in the unit?

[MikeGrahamT21]

No heaters in situ and like I said I’ve swapped the thermometers around and the error always stays the same, yes they are defo labelled correctly, have checked a million times myself months.

 

They are only cheap thermometers agreed, so how about the readings from the unit itself, do they seem right? I’ve just nothing to compare against and this is the only MVHR I’ve ever owned.

[gravelrash]

Extremely badly balanced? more extract than incoming so very efficient heat exchange to a smaller volume?

[MikeGrahamT21]

I balanced it all last year and got both extract and supply at the same overall values, so should be fine on that front, and the fan speed is set to the same, 35% normal and 50% boost