ASHP to Avoid from October 2022

No_No_No_Yes

Different surveyor and installer firms.

Discussing the pump location with the new surveyor has revealed that there might be a problem.

Not sure pump can relocated from the place that the previous surveyor had suggested, to my side of a shared drive with my neighbour... My wife thinks that the drive has to be kept unobstructed as it is fully belongs to both households.

This puts a spanner in the work as the only feasible location would need a short run of the pipework underground and both surveyors were a bit concerned that installers don't like to do this as they just want an easier job.

I would like to know how long can the outside pipework be from the pump to the HW cylinder before affecting the system's efficiency.  

Reed_Richards

No matter how well-insulated the pipework is it will lose some heat.  If the pipework is inside the insulated fabric of the building then this heat is not wasted but outside it is.  I have a lot of pipes in my loft which waste heat into my roof space.  I have tried to insulate them well but there is a limit to what you can achieve.  You'll have a similar issue running pipes underground.  At least with a heat pump the water in the pipes will be cooler than it is with other types of heat source.  

Ceol

No_No_No_Yes said:

This puts a spanner in the work as the only feasible location would need a short run of the pipework underground and both surveyors were a bit concerned that installers don't like to do this as they just want an easier job.

I would like to know how long can the outside pipework be from the pump to the HW cylinder before affecting the system's efficiency.  

I'm a bit confused why your surveyor isn't from your installer, but you could offer to do the trenching yourself to save time/money.

How long the pipework can be varies on a few things so it's hard to give you a simple answer without just giving you the formula. The main concern though is that very long pipe runs need a split system instead of a mono one. This means that instead of heating the water outside, refrigerant is pumped into your house instead and you would have an internal unit that heats the water.

I have a mono unit (ie water is heated outside and pumped inside) with a run of 10m to and from (so 20m overall) my hot water cylinder/heating circuit. The run is along the side of the house, so higher losses than an underground run, but I consider it reasonable. It's about 5% of the total power of heat pump that we'll be losing to the air when it's -4 outside.

No_No_No_Yes

Ceol said:

No_No_No_Yes said:

This puts a spanner in the work as the only feasible location would need a short run of the pipework underground and both surveyors were a bit concerned that installers don't like to do this as they just want an easier job.

I would like to know how long can the outside pipework be from the pump to the HW cylinder before affecting the system's efficiency.  

I'm a bit confused why your surveyor isn't from your installer, but you could offer to do the trenching yourself to save time/money.

How long the pipework can be varies on a few things so it's hard to give you a simple answer without just giving you the formula. The main concern though is that very long pipe runs need a split system instead of a mono one. This means that instead of heating the water outside, refrigerant is pumped into your house instead and you would have an internal unit that heats the water.

I have a mono unit (ie water is heated outside and pumped inside) with a run of 10m to and from (so 20m overall) my hot water cylinder/heating circuit. The run is along the side of the house, so higher losses than an underground run, but I consider it reasonable. It's about 5% of the total power of heat pump that we'll be losing to the air when it's -4 outside.

The surveyor has been assigned by the installer.

I have a feeling that the total outside pipework run would be around 17 lm or so.  Possibly 5 - 6 LM would need to be underground.

I wonder at what minimum depth should the pipes and insulation be?  I guess if it's insulated it could be placed at any depths?

No_No_No_Yes

The ground would be easy to dig as the base has a thin and old cement thicknes but is better that the installer digs it.  Less hustle and any problems can't be blamed to anyone else.