Suggestions for small ducted aircon unit for our plant room?

[MirandaPoth]

The 12.5m3 plant room containing our servers, switches, hubs etc in our passivhaus-standard home gets too hot (28-30 deg C). We want to install a small, efficient, ducted aircon unit to cool it down to around 20 deg C. Heating, air purification, dehumidification are not required as the MVHR takes care of those. Our water storage tank, boiler and MVHR unit are all in the same room (which probably accounts for the temperature lol).

 

We built the house ourselves 5 years ago so would like to install it ourselves. It's an MBC timberframe with wide insulated walls, cladded/rendered on the outside. We can handle making the necessary holes in the walls.

 

Is this doable, or should we get it professionally installed? Any suggestions as to type/make/model to choose? What else should we consider?

[Nickfromwales]

19 minutes ago, MirandaPoth said:

The 12.5m3 plant room containing our servers, switches, hubs etc in our passivhaus-standard home gets too hot (28-30 deg C). We want to install a small, efficient, ducted aircon unit to cool it down to around 20 deg C. Heating, air purification, dehumidification are not required as the MVHR takes care of those. Our water storage tank, boiler and MVHR unit are all in the same room (which probably accounts for the temperature lol).

 

We built the house ourselves 5 years ago so would like to install it ourselves. It's an MBC timberframe with wide insulated walls, cladded/rendered on the outside. We can handle making the necessary holes in the walls.

 

Is this doable, or should we get it professionally installed? Any suggestions as to type/make/model to choose? What else should we consider?

Do you have an MVHR extract in the plant room? I always fit one for customers where there’s a lot of kit in the same space, and that goes towards efficiency during the winter. 
 

Not so sure I’d be punching holes in an airtight PH spec build as that will be pulling a lot of air from the room and dumping it to atmosphere, which needs to get back into the building by knocking your MVHR airflow / balance way off.

 

You’d need a small “split” AC system, which seems massively overkill here. 

[MirandaPoth]

4 minutes ago, Nickfromwales said:

Do you have an MVHR extract in the plant room? I always fit one for customers where there’s a lot of kit in the same space, and that goes towards efficiency during the winter. 
 

Not so sure I’d be punching holes in an airtight PH spec build as that will be pulling a lot of air from the room and dumping it to atmosphere, which needs to get back into the building by knocking your MVHR airflow / balance way off.

 

You’d need a small “split” AC system, which seems massively overkill here. 

Thanks very much for your reply. Yes we do have an MVHR extract in the room, but it doesn't help with the heat buildup in summer. We're hoping it won't pull too much air from the room but I take your point about knocking off the MVHR airflow balance. 

 

Yes it does seem like overkill, especially as the smallest split units I've found so far are about twice the size we need. Although it would be nice to have a cool room in the house, as we are lacking one at the moment!

 

Not sure what other solutions to look at. Any ideas?

[JohnMo]

26 minutes ago, MirandaPoth said:

gets too hot (28-30 deg C).

Why is that too hot? Our is at the same temperature all summer without issues.

 

Do you have equipment failing if it hasn't failed in 3 years it's unlikely too now. 

[MirandaPoth]

Just now, JohnMo said:

Why is that too hot? Our is at the same temperature all summer without issues.

 

Do you have equipment failing if it hasn't failed in 3 years it's unlikely too now. 

Hmm I see what you mean. However hubbie is an electronics engineer and is unhappy about it running that hot all the time. Plus we have to leave the plant room door ajar all the time otherwise it gets much hotter, which isn't ideal ...

[MirandaPoth]

33 minutes ago, MirandaPoth said:

Hmm I see what you mean. However hubbie is an electronics engineer and is unhappy about it running that hot all the time. Plus we have to leave the plant room door ajar all the time otherwise it gets much hotter, which isn't ideal ...

I've just checked the running temperature of the UDMPRO. It's running at 46 deg C, which is about 6 above spec 

[garrymartin]

I'm with @JohnMo - how hot does it get when the door is shut?

 

Two things to consider...

 

1) most electronic equipment is certified to run between particular temperatures (upper, lower), and it's usually a lot hotter than you would think (we run a lot of datacenters much hotter than we did 10 years ago)

2) it may be more cost-effective to replace the equipment that is pumping out lots of heat with something more efficient that runs cooler

 

My comms cupboard at home runs above 30 degrees in the summer heat, and the equipment has no issues with that.

[garrymartin]

1 minute ago, MirandaPoth said:

I've just checked the running temperature of the UDMPRO. It's running at 46 deg C, which is about 6 above spec

OK, so that's modern equipment running above maximum specified temperature, so not great.

 

What else do you have in there that's generating that level of heat though?

[MirandaPoth]

1 minute ago, garrymartin said:

What else do you have in there that's generating that level of heat though?

Boiler, hot water storage tank, selection of HP switches, CCTV system, several servers, many small hubs for the smart home stuff, and the MVHR units itself. Hot water pipes are all lagged already, although there might be a few bits that aren't (valves, joints)

[elite]

At work we target 24 degrees for our onprem server room which has been calculated (not by me), to be the most efficient temp to run at, so I wouldn't be too concerned at 27 to 30 in a home environment, though not being able to shut the door would be an issue for me. What temp does it get to with the door shut?

 

Is there any scope to increase extract or even partition between boiler etc and tech?

 

I think 40 degrees is the max ambient temp for the UDM Pro, I expect the internal temp to maybe hit 60-70 deg under load

[JohnMo]

13 minutes ago, MirandaPoth said:

Boiler, hot water storage tank

So what temperature is cylinder kept at? That could be your biggest heat source. How well is it insulated?

[ProDave]

I would expect a modern 5 year old HW cylinder to be well insulated.  I would be looking at the pipework to make sure that is also well insulated.  Pictures?

 

Our airing cupboard is perhaps 2 or 3 degrees above the room it is partitioned from, not much at all.

[JohnMo]

8 hours ago, ProDave said:

Our airing cupboard is perhaps 2 or 3 degrees above the room it is partitioned from, not much

But you store water at circa 45, does the OP?

[S2D2]

Can you move your "several servers" to offsite hosting? These are likely the culprit and if they're doing serious work a minisplit starts to become inevitable.

[MirandaPoth]

Thanks everyone for your input. The hot water tank is well insulated and to avoid legionnaires it's at 65-ish deg C. There isn't really space to partition the room unfortunately, we thought about that.

 

Our 'several servers' are part of our smart home & audiovisual systems. The whole point for security, speed, cost etc etc is that they are on site so that as little as possible is reliant on cloud services.

 

We are getting quotes for a small split AC system; as @Nickfromwales said, this is probably the best solution. Thanks Nick 🙂

[JohnMo]

15 minutes ago, MirandaPoth said:

legionnaires

I would go on the heat geek website and read up on legionella and do a risk assessment. Heating to 50 is more than acceptable (do a risk assessment). 

 

16 minutes ago, MirandaPoth said:

65-ish deg C

Heating to 50 will just about half the heat the cylinder and piping add to the room. Storing water at 65 to 70 will release a couple of kWh of heat per day, store at 50 could reduce that to 1kWh. Which may be enough, without spending additional money.

[MirandaPoth]

Interesting! I will look that up. Thank you!

[MirandaPoth]

VERY interesting. Thank very much @JohnMo. We actually have a hot water loop in our setup, I wonder if that is enough to ensure a full change of water every 24 hours thus avoiding stagnation?

[marshian]

12 minutes ago, MirandaPoth said:

VERY interesting. Thank very much @JohnMo. We actually have a hot water loop in our setup, I wonder if that is enough to ensure a full change of water every 24 hours thus avoiding stagnation?

 

If it's a loop that supplies all the hot taps and as a result no delays in HW at the tap then it's returning to the tank and is not what I would term avoiding stagnation because legionaires isn't just about stagnation it's about controlling the temp of the water store to avoid optimum growth temps.

 

If you are using all the water in the tank every day then risk is much reduced

 

We only have a 115 Litre tank - we heat to between 48 and 50 deg C and heat just once a day (except on bath night)

 

We pretty much use all of the water every day with 2 showers morning and evening plus a little washing up

 

Is your HW loop 24/7 or on a timer to minimise tank losses - if it's on for long periods of time it will be dragging down the tank temp and as a result you need to run the tank hotter to compensate and it won't be helping the plant room temps

[marshian]

 

Easier viewing than the HG Website

[MirandaPoth]

30 minutes ago, marshian said:

 

If it's a loop that supplies all the hot taps and as a result no delays in HW at the tap then it's returning to the tank and is not what I would term avoiding stagnation because legionaires isn't just about stagnation it's about controlling the temp of the water store to avoid optimum growth temps.

 

If you are using all the water in the tank every day then risk is much reduced

 

We only have a 115 Litre tank - we heat to between 48 and 50 deg C and heat just once a day (except on bath night)

 

We pretty much use all of the water every day with 2 showers morning and evening plus a little washing up

 

Is your HW loop 24/7 or on a timer to minimise tank losses - if it's on for long periods of time it will be dragging down the tank temp and as a result you need to run the tank hotter to compensate and it won't be helping the plant room temps

The HW loop is on while we’re awake, typically 6am til 10pm. It’s off while we’re out (shopping, holidays, trips out - it turns off when our alarm is on). It’s a 250 litre tank and typically I guess we’re not using it all in a day (shower on for say 20 mins a day, a little washing up only as most goes in the dishwasher). (It’s a big tank because it’s a big house with a big bath and we didn’t want to run out when we have visitors!)

 

We’re going to fit an electronic temperature sensor on the tank to see what it actually is - currently it has only the bimetallic strip one that links to the boiler. I guess we could replace it with one that could be controlled programmatically from our Home Assistant server, so that it could periodically heat it to the higher temperature. 

[marshian]

47 minutes ago, MirandaPoth said:

The HW loop is on while we’re awake, typically 6am til 10pm. It’s off while we’re out (shopping, holidays, trips out - it turns off when our alarm is on). It’s a 250 litre tank and typically I guess we’re not using it all in a day (shower on for say 20 mins a day, a little washing up only as most goes in the dishwasher). (It’s a big tank because it’s a big house with a big bath and we didn’t want to run out when we have visitors!)

 

We’re going to fit an electronic temperature sensor on the tank to see what it actually is - currently it has only the bimetallic strip one that links to the boiler. I guess we could replace it with one that could be controlled programmatically from our Home Assistant server, so that it could periodically heat it to the higher temperature. 

so it the HW heating on demand via temp sensor (ie as soon as sensor sees 5 deg lower than target temp it tops up) or timed to once a day?

 

with a 250 litre tank and lowish usage you could run cooler temp and use more of the tank if heated once a day - if you have visitors either heat to a higher temp (change the bi-metalic sensor to higher temp or increase frequency of re-heat at same temp)

 

our tank is typically down to ~30 deg overnight and reheated in ~40 mins in the morning (using ~3 kWh of gas to do so) 

 

winter when cold water is coming in at a lower temp (10 deg) it’s down to 20 deg overnight and reheated to ~55 deg in 20 mins in the morning (house losses are increased in winter) (using ~5 kWh of gas to do so)

 

It’s what works best for us….. 

 

 

[JohnMo]

52 minutes ago, MirandaPoth said:

The HW loop is on while we’re awake, typically 6am til 10pm. It’s off while we’re out (shopping, holidays, trips out - it turns off when our alarm is on). It’s a 250 litre tank and typically I guess we’re not using it all in a day (shower on for say 20 mins a day, a little washing up only as most goes in the dishwasher). (It’s a big tank because it’s a big house with a big bath and we didn’t want to run out when we have visitors!)

 

We’re going to fit an electronic temperature sensor on the tank to see what it actually is - currently it has only the bimetallic strip one that links to the boiler. I guess we could replace it with one that could be controlled programmatically from our Home Assistant server, so that it could periodically heat it to the higher temperature. 

Sounds similar to us, but we have 210L cylinder. Generally heat twice per day, to a thermostat setting of 49, it actually settles to about 51 after heating. A lower set point means a larger turn over of water, as less cold dilution is needed. It adds efficiency to the boiler as you can set flow temperature lower.

 

I keep DHW away from home assistant, I tend to keep all systems that I need simple and well detached from anything so called smart.  DHW is local controller - a simple time switch between the thermostat and heat source, heating is now just weather compensation and not even a controlling thermostat, just a manual switch between cooling and heating.