Install the air/water heat pump outdoor unit indoors

Good day,

we want to install an air/water heat pump in the company to pump the waste heat from our servers into the return flow of the heating system. Therefore, we have chosen a two-stage air/water heat pump. Namely the Rotex HPSU hitemp.

However, we also want to install the outdoor unit indoors so that the heat from the room can be used. Therefore, I think it should not be a problem, since only the heat is "sucked out." However, the manufacturer could not help us with this, nor can I find any information about it on the internet.

That is why my question to you is: Can the outdoor unit also be installed indoors?

Thank you for your help!

Best regards

Leon Heilmann

Where does the necessary supply air come from? Do the servers handle the high airflow? How much heat load do the servers emit?

The idea itself is great, but your approach to implementation is nonsense!

Please do not do such a makeshift job and install a device intended for outdoor use indoors. Otherwise, you will have a massive moisture problem in the server room due to the resulting condensate failure. In addition, the entire system dimensioning of an outdoor unit is set for completely different parameters than what an indoor space can provide.

What would be possible: Use an exhaust air heat pump; these are specially designed for indoor installation and are usually dimensioned for hot water production.

Otherwise: How many servers, how much waste heat actually occurs, how is the integration into the heating/hot water hydraulics, and very importantly: You also have to somehow supply cool air.

Furthermore, it is important that you have a cold/warm zone separation so that it works efficiently and you don’t let your servers die from heat because the heat pump pulls the air around it away. The little fans in the servers then get no throughput if one or even two large fans from an outdoor unit start to generate considerable pressure. Here again, the dimensioning of an exhaust air pump is advantageous.

First of all, thank you for the quick and helpful responses.

We currently have two air conditioning units outside to get the cool air into the server room. So I think there is no lack of fresh air.

And since the servers are built into cabinets that only get airflow from the floor of the air conditioning system and are also "exhausted" again, the fans should still have throughput.

We have 5 server cabinets with a total of 10 servers, 5 hard drive bays, and several switches.

I will follow up on your tip about the exhaust pump and inform myself about it.

Again, thank you for your help!

10 servers + 5 JBODs distributed over 5 racks are not particularly densely packed, meaning you have a relatively cool exhaust air flow. This makes the air concept all the more crucial to avoid mixing losses.

If I assume average mid-range machines, depending on the load of the machines, you will be between 3kW and at most 8kW of electrical power. You have this 1:1 as thermal energy at the machine, plus possibly the waste heat from UPS/power distribution. The waste heat from lighting, people in the room, and other sources can be neglected given the very manageable size.

However, what is crucial is the quite exact knowledge of the amount of waste heat in kWh. The heat pump must be dimensioned accordingly. A heat pump that is too large will ruin your climate concept.

Otherwise, someone with experience in the MEP sector for data centers should still inspect the site. Simply saying "cold air comes from the raised floor" is unfortunately not enough. You need to know the flow and mixing conditions to have a sensible concept, the racks may possibly need to be sealed more than before, etc.