I’ve recently experienced an issue with an airlock developing in the gravity-fed water system. The plumber has now attended twice to resolve the problem and has suggested that the cause may be the Aqualisa shower pump drawing water from the main cold-water storage tank in the loft faster than it can replenish.
The plumber has advised that the shower should not be used for extended periods to avoid the tank running low and potentially causing the problem to recur.
My concern is around responsibility should this happen again. If the airlock continues to develop as a result of normal shower use, would the responsibility and associated cost of getting a plumber out to resolve it fall to the landlord or the tenants?
At present, there is no clear indication of how long the shower can safely be used before the loft storage tank runs low. Equally, this is not something that can realistically be monitored or measured, which could potentially lead to disagreements in the future.
I would appreciate some advice on the best way to address this. Ideally, I’d like to establish whether there is an underlying issue with the plumbing or shower installation that needs to be rectified, rather than relying on restrictions being placed on normal shower use.
I dont see that you can restrict shower time or that it would be tenants responsibility.
If shower is very powerfull you could offer to replace the showerhead with one that restricts water flow which would reduce tenants energy and water bills but not sure if you could enforce this if they dont want that.
Get more specific advice from plumber on options, we dont know the set up, but sounds like not enough pressure from tank above - but not sure how that would introduce air bubbles unless the water is actually running out. could be you need
A) bigger tank
B) replace with a low water usage shower head or lower water usage shower
C) a push button switch which turns shower on for only a limited period to encourage shorter showers (have seen these used in some youth hostels for example for environmental reasons
D) adjust ballcock in tank so it fills up sooner
E) pump connected to pipework from tank to shower that increases pressure when shower turned on (these cost around a hundred quid if i recall but need plumber to install)
F) try tell tenant not to take showers longer than 10min otherwise if plumber called out for same issue they will have to pay. If issue is being caused by excessively long showers of the tenant it’s fair for them yo reduce just like you would if issue was in your own home
I had similar with a tenant who filled up a bath, the pipe to the bath was 22mm and supply to the tank 15mm., result airlock This was in the era of immersion heaters. When i had all combi boilers fitted, supply to bath now15mm. no more probs.
What would happen is the tank level drops quicker than the input. and glug , glug, air goes down the pipe along with water. Thus airlock .. 90 degree bends compound the issue and a pump in line cannot work properly
I’ve asked for a second opinion from another plumber who will visit the tenants later this week. He has experience of installing Aqualisa shower systems so hope he can find a solution.
I would expect the cold tank in the loft to refill from the mains supply at a rate that is roughly similar to the rate of water drawn by the Aqualisa shower pump.
Good luck. Suspect tank and gravity feed is because not on ground floor/not enough pressure from mains so whatever you do there is a limited capacity of water in the tank. Without a different solution (such as a pump to boost the pressure and flow rate from mains entering the property), if they take unduly long showers maybe the water from a tank runs out - if the inflow rate was as high as the shower you wouldnt need a tank would you? Just like if hot water comes from a tank heated overnight in an immersion heater, it runs out too if too much is used.
Good point from @Colin3 too - multiple people taking showers at same time will also reduce pressure.
If bills are included the tenants might be taking hour long showers without a care. If you make them pay the bills or say that further unnecessary callout due to air bubbles in the system will be charged to rhem, that might change.
Depending on how good the incoming mains pressure is, any plumber who knows what they are doing can check this, why don’t you swap it over to everything is mains fed? Easy to do, if pressure is constantly good, just literally in simple terms connect the inward to the outward on the CWST. Likely need to replace the shower for one that is capable of handling mains pressure which are easily available otherwise the existing one will blow the seals or a tiny clear ball out of the bottom so do not think it’ll be ok, it never will be unless the shower is mains pressure safe. Yes you may need to change the WC inards slightly more often, but still talking years apart, same for the other taps. I’m a retired heating engineer and plumber plus a significant landlord. That’ll solve the issues if pressure good but it’ll cost you a couple of hundred pounds