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Gurgling, dripping, funny sounds coming from our buffer tank / hot water cylinder
When we had the ASHP installed, we also put in a new hot water cylinder with buffer tank. This tank has always been extremely quiet, and occasionally we'd hear gentle water filling the cylinder after a shower or when we used a lot of hot water.
Over the course of the past fortnight, we've been using our oil boiler more frequently in condensing mode (especially at nighttime) when it's cold outside and the efficiencies of the heat pump suffer – with current tariffs, low efficiencies are a financial killer. We're also hoping to get our first delivery of HVO soon to replace the kerosene. Coinciding with this, we've noticed that our tank has become a lot noisier – it makes strange gurgling and dripping sounds that seem to be emanating from the buffer store, but it's difficult to know for sure.
I've posted a 10-second video below to illustrate the sound. There's nothing exciting visually, just some pipes. The sound in this video is more of the dripping, running water sound. Will try to capture the gurgling later.
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Posted by: @editorWhen we had the ASHP installed, we also put in a new hot water cylinder with buffer tank. This tank has always been extremely quiet, and occasionally we'd hear gentle water filling the cylinder after a shower or when we used a lot of hot water.
Over the course of the past fortnight, we've been using our oil boiler more frequently in condensing mode (especially at nighttime) when it's cold outside and the efficiencies of the heat pump suffer – with current tariffs, low efficiencies are a financial killer. We're also hoping to get our first delivery of HVO soon to replace the kerosene. Coinciding with this, we've noticed that our tank has become a lot noisier – it makes strange gurgling and dripping sounds that seem to be emanating from the buffer store, but it's difficult to know for sure.
I've posted a 10-second video below to illustrate the sound. There's nothing exciting visually, just some pipes. The sound in this video is more of the dripping, running water sound. Will try to capture the gurgling later.
Hi Mars,
Sounds like you have air in your system, make sure the air relief valves are not full closed.
Hi Mars,
Derek is spot on - we had this with our installation which I mentioned on my thread. It sounded awful and we had to switch the entire system off and get the installers back in, it turned out the system hadn't been fully pressurised. This was sorted out quickly enough and has been fine since, they did show me the small red buffer tank (which nobody showed me before!) and there is a dial-type pressure which you can add to easily and sort any pressure issues.
Thanks Derek and Siko.
Our AAV (automatic air valve) is closed and our system is fully pressurised - I check our expansion vessel a few times a week because we've had issues before, and I release the trapped air from the valve a few times a week. I recently discovered an AAV on the oil boiler too which our boiler service guy said should remain open. I'll probably shut that off and release air when it builds up.
Hopefully this is just air, and I'll continue to monitor the sound.
🔥 Britain’s Heat Pump Shitshow
How Installing a Heating System Became a National Nervous Breakdown
Free UK shipping.
📗 Heat Pumps Explained
A Jargon-Free Guide for Homeowners
Rewritten and updated for 2027
📘 From Zero to Heat Pump Hero
🛠️ Bodge Buster
New to heat pumps?
Take the Heat Pump Fundamentals course and use INTRO50 at checkout for 50% off.
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