ASHP vs water source

[H F]

I came across an interesting read this morning that spoke about using water as a heat source for homes - a la ASHPs - which is much more efficient.

 

I was wondering how much water you need to heat your property - we have a bricked Victorian well in our courtyard which holds a fair amount of water. What the article didn’t go into is the type of pump you’d need to extract the heat.
 

As we’ve already invested in an ASHP, is there a way of getting them to work together if the water source was viable?

[ProDave]

This is what's generally known as a ground source heat pump.  It extracts heat from water, instead of from air.

 

Arguably they are more efficient and don't need to defrost like an air source heat pump has to sometimes.

 

The downside usually is they use a lot of pipes laid in the ground circulating brine as their source, or a borehole, both of which are expensive to install making them a lot more expensive than an air source heat pump so probably less good value for money.

 

The well may work as a heat source, providing the water is refreshed somehow, otherwise you might just end up with a frozen well in the winter.

 

I thought about using our burn as a heat source but to do it legally would require an extraction licence.

[H F]

Thanks Dave. Do you know whether it’s possible to run and ASHP and water source pump through the same system? 
 

From my rudimentary understanding if things, I’m guessing not from a piping perspective.

[ProDave]

Nothing to stop you having two heat sources with appropriate valves and controls to select one or the other.  But it seems an unnecessary cost and complication.

 

The other thing that puts me off ground source, is the compressor is inside the house somewhere, purring away like a fridge a lot of the time.  I prefer the noise outside with  monoblock ASHP.

[SteamyTea]

Do you mean a water source heat pump. As is one that pumps river, lake or sea water into a heat exchanger, then through a heat pump as normal.

Or a ground source heat pump, but with the brine pipework in water, rather than the ground.

You can calculate the energy in a fixed amount of water easily enough.

4.18 kilo joules x mass or flow in Kg x drop in temperature in K.

It is the same as how much energy us needed to heat water.

[patp]

What about hydro power? We have a spring running through our property that is fed by a leaking bore hole to the North of us. It is quite fast flowing and we are thinking that it might make a good source of hydro power.

[H F]

6 minutes ago, patp said:

What about hydro power? We have a spring running through our property that is fed by a leaking bore hole to the North of us. It is quite fast flowing and we are thinking that it might make a good source of hydro power.

I’ve already started a topic on this one before: 

 

 

 

[H F]

3 hours ago, SteamyTea said:

 

Do you mean a water source heat pump. As is one that pumps river, lake or sea water into a heat exchanger, then through a heat pump as normal.

 

I was thinking of this option, but I’m wondering whether installation costs would prohibitive. I assume there would be RHI payments. Hmm.

[SteamyTea]

You may also need a water extraction license.

[patp]

Thanks I have looked at the existing thread but they all talk about using a turbine. We are thinking of different ways as the water flow is about 1 litre per second so we were told by a visiting Anglian Water bod.

[ProDave]

How much head do you have?

[SteamyTea]

34 minutes ago, patp said:

1 litre per second

 

10 minutes ago, ProDave said:

How much head do you have

 

Does it matter

[ProDave]

18 minutes ago, SteamyTea said:

 

 

Does it matter

Yes.  If like is you have barely 1 metre head from end to end of the plot, you are not going to do much with a turbine, and when the time comes, I am going to experiment with an undershot water wheel instead.,

[Triassic]

Is it cost effective? Others on here have questioned the payback time, particularly when you consider just how cheap electricity is if taken during the night? Why not use a Willis heater and save the thousands it will cost to install a gro7nd or air source heat pump?

[SteamyTea]

14 minutes ago, ProDave said:

If like is you have barely 1 metre head

If you had 100 metres of head, at a flow rate of 1 litre/second, 95% efficiency you would only have 932 W.

Trouble is, pico-turines are not very efficiency, they are like small windturbines.

[ProDave]

3 minutes ago, SteamyTea said:

If you had 100 metres of head, at a flow rate of 1 litre/second, 95% efficiency you would only have 932 W.

Trouble is, pico-turines are not very efficiency, they are like small windturbines.

I think I would be lucky to get 50W from what we have.  If I ever experiment with it, it will be for fun and interest, not because I think it will be financially viable.

[patp]

We have nearly 1 metre of head and the flow never stops.

[joth]

I know it's OT for your question here, but if you're looking at a secondary heat source have you considered biomass? That would seem more complimentary as it can remove the dependence on electricity supply (or at least, on electriciry pricing), is better suited to large buildings with lower levels of insulation and rural settings, and has a lower effective CO2 cost. 

 

 

 

[SteamyTea]

13 minutes ago, patp said:

We have nearly 1 metre of head and the flow never stops

So that will be, 1 [kg.s^-1] x 9.81 [m.s^-2] x 1 [m] x 0.95 [eff]

9.3 W

Run it for a year

81,639 Wh = 9.3 [W] x 8760 [h]

Call it 82 kWh

 

[SteamyTea]

2 minutes ago, joth said:

and has a lower effective CO2 cost. 

You may have difficulty convincing a lot of people of that one.

[ProDave]

2 minutes ago, SteamyTea said:

So that will be, 1 [kg.s^-1] x 9.81 [m.s^-2] x 1 [m] x 0.95 [eff]

9.3 W

Run it for a year

81,639 Wh = 9.3 [W] x 8760 [h]

Call it 82 kWh

 

or about £12

[SteamyTea]

£7.70 for my E7 with VAT.

About the same as running my laptop.

(if i put a full screen white picture up, I could read by it)

Edited January 14, 2020 by SteamyTea

[joth]

4 hours ago, SteamyTea said:

You may have difficulty convincing a lot of people of that one.

Honestly, I have difficulty convincing myself of it, but there was a lot of data thrown at me last night showing the point. (Based on survey from last month of the national average CO2 costs of acquiring pallets vs generating electricity during the heating season. Obviously any given individual's mileage will vary). I can't find the reference now of course, I will request it. Best I can get is this which backs it up (factor 7x more CO2 for ASHP) but it's well out of date.

[SteamyTea]

8 hours ago, joth said:

acquiring pallets

I think they may be on the list of stuff that is not allowed to be burned.

[canalsiderenovation]

We looked into a water source heat pump and using blades (can be used in flowing water). The name of the company I can't remember but they actually cam and visited our site and were incredible helpful. This was about 12 months ago even before we got pp approved (just approved a week ago). 

 

It was slightly different as we have a by wash from the canal and whilst the technology itself may have been an option, the stumbling block for us was the Canal and River Trust. Anything to do with using 'their' water means all sorts of applications, fees and red tape, things like extraction licences etc etc. They weren't the most approachable people. Instead we are now going down the ASHP route.

 

Edit, these were the blades https://www.nuenta.com/viewproduct.asp?pid=109

Edited January 16, 2020 by canalsiderenovation
Edit