Rf signal booster help

hi all
I have fitted a centre brand wireless rf programmable thermostat to a boiler in a large house, boiler sited in the cellar and programmer upstairs.
Customer has complained of not being able to control heating, when he goes down in the cellar the light is red on the little box,does anyone know of a way I can boost the signal through the thick walls as I'm sure this is the only reason it isn't picking up the signal, have tried different rf stats to see if that was faulty but no joy.
Thanks for any help

 

I know hive do booster plugs so that you can overcome these problems but depends if customer is interested in that side of it.

 

Can you not site the control box further towards the center of the house, or does it have to be next to the boiler.

 

If practical, try running a cheap wire (e.g. bell wire) from near the transmitter to the receiver. Don't make contact at any point, but form a flat coil of the wire and mount it under the receiver box. I've done it for RF stats where transmitter in large house and receiver in detached garage some distance away and it works.

 

Thanks for all replies