DIY – A more stable water supply – Coping with summer demand

Finally I came round to address the water supply for our houses and the garden. We have a powerful pump - submerged (it’s much quieter than the above ground) and had small expansion vessel (Calderin) fitted of about 25Liter.

standard calderinWell, water can’t be compressed but be put under pressure. So as soon as one opens a tap, pressure goes, specifically if, like us, you have a system that holds very little water. Calderins (expansion vessels) have air or nitrogen in it which can be compressed. These vessels have the advantage to absorb pressure fluctuations and shock waves which are generated when a pump engages or a tap / vent is closed fast. This is not a huge problem but does put stress on the system. 

There are pressure / flow control systems that in theory do not require expansion vessels, but standard pumps my take up to 8x the power when starting so “soft-start” electronics is required, also each time a glass of water is filled the pump may start. There are single phased pumps whose delivery rate can be controlled, but again this is advanced and pumps tend to be less effective if throttled back. I’m aware of these possibilities but try to use standard equipment / materials as much as possible, so in case of problems it’s easier to rectify.

Another problem is that systems never tend to be totally water tight. Come on, there is always a tap or an outside connection that drips, or the hose connections are now longer spanking new.

With the increasing garden here there is also growing demand for individual watering, thus small amounts of water in very short bursts.

Lately, probably due to a defective air vent of the existing calderin the pump had to switch on fairly often.
Whilst taking a shower the pump switching was always noticeable but became more increasing.

Normally this can happen because here the calderins are mostly without membranes and the air cushion slowly but surely dissolves into the water over time. Thus all have a standard car air vent to re-pressurise with a compressor or a simple car tyre pump.

50L upright expansion vesselNow I’ve fitted a 50Liter upright. I haven’t pressurised it as in our system we don’t have a lot of water. No boilers etc, just straight pipes and hot water by gas on demand. I run the system between 3 – 3.75Bar (at point of distribution not at the water table) – the pump easily delivers 8Bar. Our maximum head is only about 20Meters (water level to shower head) so allowing for a little pipe friction (feeder pipe well to distribution is 32mm) I would get 5.5Bar if I wanted to.

Now with the new calderin the pump switches rarely, and if it engages, it runs for a decent time before being triggered off. The water flow has become smooth and regular.

So my tip: If you can fit it, fit a larger expansion vessel than strictly nessesary. Make sure you can easily reach the air vent. Also if you are not regular using the system it maybe advisable to put in a three-point valve so you can drain the calderin. Another advantage the bigger, the less insulation it needs when installed outside to prevent freezing.

So here is to “the summer is easy”

summer is easy