These readings are for a cavity wall with no insulation. The external vent is blocked with insulation, cavity RH is continually monitored and varies from 70% - 80%.

Indoor temp 18C
Cavity temp: 2-3C
Outdoor temp: within a few degrees of zero each way

Why?


NT

On 08/02/2018 00:15, wrote:
These readings are for a cavity wall with no insulation. The external vent is blocked with insulation, cavity RH is continually monitored and varies from 70% - 80%.

Indoor temp 18C
Cavity temp: 2-3C
Outdoor temp: within a few degrees of zero each way

Why?

Despite the blocking of the external vent, could it be that there is a
draught in the cavity, constantly introducing new air? I don't think
cavities are ever properly sealed. Often the top of the cavity is open,
under the tiles.

Bill

On Thursday, 8 February 2018 04:15:47 UTC, Bill Wright wrote:
On 08/02/2018 00:15, tabbypurr wrote:

These readings are for a cavity wall with no insulation. The external vent is blocked with insulation, cavity RH is continually monitored and varies from 70% - 80%.

Indoor temp 18C
Cavity temp: 2-3C
Outdoor temp: within a few degrees of zero each way

Why?

Despite the blocking of the external vent, could it be that there is a
draught in the cavity, constantly introducing new air? I don't think
cavities are ever properly sealed. Often the top of the cavity is open,
under the tiles.

Bill

I think it proves that the wall above is cavity construction, which was uncertain, and that the top is open. That means a practical insulation opportunity.


NT

On 08/02/2018 00:15, wrote:
These readings are for a cavity wall with no insulation. The external vent is blocked with insulation, cavity RH is continually monitored and varies from 70% - 80%.

Indoor temp 18C
Cavity temp: 2-3C
Outdoor temp: within a few degrees of zero each way

Why?


NT


Go round all your upstairs sockets, unbolt the socket and hold your face
close to it. Do you feel any cold drafts ?.

Air-leakage through a cavity can be extreme and all your heat end up
in the loft.

On Saturday, 10 February 2018 15:02:55 UTC, Andrew wrote:
On 08/02/2018 00:15, tabbypurr wrote:

These readings are for a cavity wall with no insulation. The external vent is blocked with insulation, cavity RH is continually monitored and varies from 70% - 80%.

Indoor temp 18C
Cavity temp: 2-3C
Outdoor temp: within a few degrees of zero each way

Why?


NT


Go round all your upstairs sockets, unbolt the socket and hold your face
close to it. Do you feel any cold drafts ?.

Air-leakage through a cavity can be extreme and all your heat end up
in the loft.

It has to be cavity all the way up, and has to be open at the top. What else would account for the readings?

If brush strips can be got into the right places, which would be a major challenge, then at least its CWIable. They would need to travel horizontally from a removed air vent, there's no other access. I don't know how to do that.


NT