Dunham Bush Heat pump

[Miked1]

We recently installed a 48000 BTU heat pump into an insectory with humidfier etc. and the client requires an indoor temperature of 34 Deg C. and 98% humidity. During the warmer weather we were able to maintain these temps in the room but now that the ambient drops at night to below 7 DEG C the indoor temp is dropping to about 21 Deg C. We recommended installing electric heating to compensate for this but the client is adamant that he doesn't want electric heating as this will increase his electric bill. Does anyone have a solution for this problem.

[hyperion]

You could try modifying the condensing unit by putting in a four way valve and the associated controls to turn the unit into a heat pump.
This would be quite an extensive and expensive project as there would need to be a considerable amount of experimentation until you got the system balanced to meet the heating demands and prevent the compressor from short cycling.
An electronic temperature controller and shuttling the four way valve could give quite close control.

[The Viking]

Well,
You would have to take another look at the heating demand and compare it to the output from your heat pump at the ambient temperatures you are likely to experience.

At the moment, assuming there is nothing wrong with the heat pump, we know that 48000 BTU is not enough to keep the room at the desired temperature. Will another 48000 BTU heat pump do the trick? Quite possible but do remember to look in to the finer details of the spec. the 48000 BTU rating will be at specific in- & out-door temperatures, quite possible the indoor temperature set to reach 48000BTU is around 20ºC and you will find that at 34ºC not much capacity is left.