Whole House Solution

[Paolo]

Hello good plumbing folk. I am a newcomer to this forum and am trying to work out a good water solution for my somewhat unconventional situation. In my own “special” way, I have a solution worked out in my head but was looking for any advice from anyone that actually knows what they are doing. I shall endeavour to explain what I plan to do but please excuse my lack of plumbing knowledge!

So to set the scene I recently purchased a rural place in Gloucestershire with no mains water. Water is supplied via a borehole from the garden. The borehole pump works with a pressure vessel so effectively delivers mains pressure to the house. This works ok, but we are renovating the house and will need very good pressure to power two showers (one main bathroom, one ensuite).

Hot water is provided by a ground source heat pump which uses an unvented pressurised tank so is pretty conventional in that respect. Currently there is no cold water tank and the feed from the borehole goes directly to cold water outlets and directly into the hot water tank. The pressure from the borehole pump will currently provide a mediocre shower, but is severely affected when any other tap in the house is used, and also I can notice the pressure drop and increase as the borehole pump cycles when the pressure switch kicks in and out. As I will soon have two showers to power that may well be used simultaneously I need a more stable and powerful solution. I have considered ways of increasing the pressure from the borehole pump, but I have decided that in order to get the best performance I will need to a cold water tank in the loft and utilise additional booster pumps.

I have attached a diagram to try and explain what I am planning. I will still utilise the pressure from the borehole for all cold water taps and appliances EXCEPT the cold feed for the showers. The borehole feed will also fill a loft tank, and by means of a floaty ball valve, keep it filled. The tank will have two direct feeds to two different Salamander ESP 80 CPV booster pumps. One pump will supply cold water to the showers, and one will supply water to the heat pump to keep the hot water pressurised and to provide good hot water pressure to showers. This “hot water”pump will also have to feed the rest of the hot water taps in the house, but I cannot think of any other way of getting hot water to them (I was kind of hoping that the salamander pumps would exclusively power the showers)

So is this a viable solution? I hope what I have written and my distinctly amateur diagram make sense, any comments welcome, I will not be offended if this is considered to be complete BS!!!

I shall try to pre-empt some questions that people might have below:

Q: Why have I used two different pumps instead of a combined hot/cold booster?
A: I already have one Salamander ESP 80 CPV from a previous plumbing endeavour, so thought I would just double up for a hot/cold solution

Q: why don’t I use the salamander pump to boost all the cold water outlets in the house?
A: because the borehole pump provides sufficient pressure for these taps, and using this setup will eliminate any pressure drop in the shower if an appliance is working or a toilet flushed during shower. Also no noise from borehole pump if for example dishwasher is on overnight (borehole pump is 50 metres underground so pretty quiet!)

Q: Why have I only used a 2.4 bar pump?
A: Because the hot water tank in the ground source heat pump can only take 3 bar max

Q: What have I placed the hot water pump before the hot water tank not after it
A: This is because the tank is double skinned and is surrounded by the hot water tank for the central heating system. If any booster pump drains this tank too quickly without refilling I risk badly damaging the hot water tank. The supplier of the heat pump has recommended that any booster pump is installed prior to the hot water tank.

 

[Ermintrude]

I would go accumulator pump with DCW store feeding hot and cold at 2.5 bar and 30l/m. No booster pumps. Unvented thermal store?

 

[hammers4spanner]

Whats your trade???

 

[Paolo]

Whats your trade???

Network Engineer - professional button pusher

 

[happyflyer]

Sorry I missed the bit about low flow from the borehole, I take it the pump is a multi stage bottom of borehole suspended on the riser pipe and that may not be easy to replace, is there plenty of room in the roof space to put the tanks, have you measured the pressure and flow rate from the borehole. Is there a problem with the pipe from the borehole head to the house, how long is it and what dia. Do you know how deep the pump is down?

 

[hammers4spanner]

i would suggest you get an appropriate drawing and spec by someone who has PI insurance otherwise i could see some poor sod running around getting stressed over this.

Nothing worse than someone who wants to be a building surveyor and then the trades trying to work off this been their done that dont work .

good luck in trying tho

 

[stevetheplumber]

sounds to me that there is enough presure but your lacking in flow rate i n=know nothing about bore holes but wouldnt the simple solution be another or larger pump at the bore hole ?

 

[happyflyer]

Steve,

Boreholes usually have a mutli stage pump screwed onto the end of steel pipe and it is lowered down the hole on the steel pipe, it could be 20 or 30 ft down, 2 lengths of galvanised pipe, the power cable is clipped to the pipe all the way to the bottom. Some pumps are rather heavy and you need gantry to get them out with lifting gear so changing the pump could be a pain, the diameter on the borehole will also dictate water size of pump you can lower down there, this is a tough one, nice not to have to pay a water bill but a mains supply would be much better.