Can you solve this mystery?

Verdigris

There are a lot of variables in this equation, some of which we may not be aware of/can quantify, but given sufficient data, I go with the science.

QrizB

digannio said:

I don't think this can usefully go much further.

I'm pleased that we helped you find the mystery 10kWh drain, and that you are able to stop it recurring.

digannio said:

Enjoy your New Year.

Thank you, and I hope you do too.

Petriix

Great, if you're happy to accept that blowing cold air into your house somehow doesn't make it cold. I wish I had a way of heating the air by 10-15 degrees without using any energy at all.

Anyway, I'm glad you discovered the source of the extra electricity usage. I look forward to your next thread about what could possibly be adding 10% to your gas usage.

Gerry1

Petriix said:

I look forward to your next thread about what could possibly be adding 10% to your gas usage.

Assuming the OP's boiler operates around 10 - 24kW (ball park) and that the 0.4kW PIV electric heater is correctly dimensioned, an increase to 10.4 - 24.4kW in gas output will be far less than 10%.

Grizzlebeard

Petriix said:

.......

That's objective fact. Basic physics. Not opinion or anecdote.

It's totally fair enough if you're happy to spend that additional energy on having a well ventilated and condensation-free house. But it's nonsense to pretend that there is no cost. .......

If there's some flaw in my logic then please point it out. The wasted energy is the only reason why I have chosen not to install a PIV system myself.

There is another physical mechanism for heat loss that nobody has yet mentioned -  Enthalpy of condensation.

When the water vapour in the air in your house condenses on the coldest spot it can find, say a window pane, it's transferring it's latent heat of evaporation directly to the least thermally insulated (coldest) place in the room, which in turn is conducting it to the outside.

The system is acting like a fridge where the water vapour/condensate cycle is the refrigerant.

I don't know the maths, but I wouldn't be surprised if the heat lost by cold PIV air coming in was going to be lost anyway on the cold condensing surfaces, thus making the system thermally neutral.

There are so many PIV users who report it doesn't cost more to heat, and many non-users insisting it must.

Maybe this theory is the "Basic physics" that squares the observed data with "objective fact" rather than "opinion or anecdote".

Reed_Richards

I bought a humidity meter.  So far it has told me:

1. The Relative Humidity inside my house is a lot higher in summer than in winter.
2. The Relative Humidity outside is almost always greater than it is indoors.

Does this make by locale unusual?  It's hard to believe that a PIV system would do me any good under these conditions.
  

Spies

Don't forget it's Relative humidity. 

Therefore if you're seeing 90% humidity outside an the temperature is 3c, it's still worth opening the windows because that same air heated to 18c is only 35% RH.

Objectionally, it takes more energy to heat damp air, so maybe the PIV system, with its dryer air, is more efficient to heat than if it was wet, therefore the xtra heating requirement is possibly balanced out?