Hypothetical question re ASHP

[mjc55]

So we are currently planning the main part of our build but are also pretty sure that we will build a office/store in a separate structure.  This we will use to live in while we build the main house.

 

I don't know an awful lot about ASHP but we are planning  to use as our heating system.

 

The question of heating the "temporary" living accommodation is one that I haven't really sorted but I was wondering if it is possible to install ASHP by the office/store (where we would want it ultimately anyway)  approximately 15 m. or so from main house.  Main house will be around 130sq. m., single storey, office/store around 25 sq. m. or so.  Could we then "throttle down" the ASHP to heat only temp. accommodation for the duration of the build and then connect it to main house on completion?

 

Any thoughts most welcome.

[JohnMo]

Certainly doable, throttling not really, but the heat pump will modulate to reduce output.

 

Depending on ASHP size and heating duty and system volume a buffer/volumiser is going to be required. 

 

A possible solution would be a fan coil these run on a just about fixed 35 degs water temperature. So easy to set up, we have one in our summer house (used 365 days a year) and UFH in the house, all run from a single ASHP. It was a bit of a learning curve setting up, but works well now.

[JamesPa]

9 hours ago, mjc55 said:

So we are currently planning the main part of our build but are also pretty sure that we will build a office/store in a separate structure.  This we will use to live in while we build the main house.

 

I don't know an awful lot about ASHP but we are planning  to use as our heating system.

 

The question of heating the "temporary" living accommodation is one that I haven't really sorted but I was wondering if it is possible to install ASHP by the office/store (where we would want it ultimately anyway)  approximately 15 m. or so from main house.  Main house will be around 130sq. m., single storey, office/store around 25 sq. m. or so.  Could we then "throttle down" the ASHP to heat only temp. accommodation for the duration of the build and then connect it to main house on completion?

 

Any thoughts most welcome.

As @JohnMo says you are almost certainly going to need to add some volume to the system when it's heating the office only (ASHPs typically specify a minimum system volume). 

 

If you happen to have an old dhw tank lying around you could probably repurpose this as a volumiser (basically a big tank that you plumb into the return).  If not, and since you probably want to avoid the buffer tank in the final build, you would probably be better just putting an electric heater in temporarily.  

 

Have you got the heat loss calcs or estimated loss per square m yet?

 

 

[mjc55]

1 hour ago, JamesPa said:

As @JohnMo says you are almost certainly going to need to add some volume to the system when it's heating the office only (ASHPs typically specify a minimum system volume). 

 

If you happen to have an old dhw tank lying around you could probably repurpose this as a volumiser (basically a big tank that you plumb into the return).  If not, and since you probably want to avoid the buffer tank in the final build, you would probably be better just putting an electric heater in temporarily.  

 

Have you got the heat loss calcs or estimated loss per square m yet?

 

 

No heat loss calcs yet, just in the design phase.

[sharpener]

11 hours ago, JohnMo said:

Certainly doable, throttling not really, but the heat pump will modulate to reduce output.

 

Many HPs have a noise reduction mode which produces less output in a slightly more controllable way.

 

1 hour ago, JamesPa said:

If you happen to have an old dhw tank lying around

 

Or buy the dhw tank you will eventually need (with a big coil to suit the HP). Pipe it up temporarily as a buffer/thermal store and draw the dhw off through the coil while you are living in the office/store.

[JohnMo]

1 hour ago, sharpener said:

buy the dhw tank you will eventually need (with a big coil to suit the HP). Pipe it up temporarily as a buffer/thermal store and draw the dhw off through the coil while you are living in the office/store.

Not sure about that due to contamination for later use. Plenty of cheap cylinders on gumtree.