Very high water consumption

[JX350C]

Hi everyone,

I moved into a new build three bedroom, two bathroom bungalow about 2.5 years ago. Ever since we moved in there has been an issue with the water pressure.

Toward the end of last year the pressure had got worse. For instance, you could not run another tap in the house if a toilet was refilling or if someone was in the shower. If someone was running a bath then all taps in the house would have no water supply to them and the toilets wouldn't refill if flushed until the bath was stopped.

So we telephoned our water provider to see if this is normal for this area or if there were any known issues with the supply in our street.

To our suprise they said that they have noticed that since we have moved into the property that we have been using very high amounts of water.

I can't see us consciously being users of a large amount of water. We have a shower most days and sometimes have a bath instead. We have a dishwasher and washing machine. The dishwasher is used about once a day and the washing machine is only used maybe twice a week at most. The showers we have are mixer type without any power assistance.

The water company have so far been very helpful and asked us to undertake some simple tests to try to identify either a leak or something else in the house using large amounts of water.

The first thing they asked us to do was to ensure the stopcock in the house was fully open. To my surprise I found the stopcock in the house to be only about half open. I thought that when we moved in that this was all setup correctly. I did check the stopcock before calling the water company but I could not turn it. After checking it again following speaking to the water company I managed to turn it until it was fully open. I think it had got a little seized so just needed more brute force to open it fully. Once I had opened it fully, we had full water pressure and we could use the taps at the same time as running a bath or flushing the toilet. The water that came out of the taps and toilet however was brown for a while and it then settled back to clear water.

So the water pressure issue was resolved.

But the water company stated we were using very large amounts of water so we needed to test for a leak between the meter in the street and the stopcock in the house.

So I fully turned off the stopcock and took a meter reading. I waited an hour and checked the meter again and it had not changed. So the water usage was from something or a leak in the house.

So I turned the stopcock fully open again and started to monitor usage by taking regular meter readings.

To my horror I could not believe the difference between the meter readings. Between the readings we did not use any toilets, showers, didn't have any baths and did not have the washing machine or dishwasher on. We didn't use any of the taps so I thought the readings should not change.

The first meter reading that I took, after opening the stopcock in full, was from overnight and it indicated that we had used 130 litres of water overnight.

I've been doing further readings with the stopvalves to individual items closed and without using any water from taps etc.

Overnight last night we have used 394 litres of water. Again, we did not use any showers, toilets, baths or taps during that time.

So with everything off we were still using lots of water for some reason.

So the only thing left that I could think of was the underfloor heating and water heating that is in our laundry cupboard.

So I switched off all the underfloor heating controllers in each room and ensured the manifold actuators were all closed. I then also switched the hot water controller to off instead of it using the timer schedules.

I took a new meter reading and waited an hour and to my suprise we had now only used 3 litres of water. I left it another hour and took another reading and that time we had used 1 litre of water. However, we did not use any taps or any water during that time so even with the heating and hot water off we still have some form of water leak/usage somewhere.

My first concern is why the underfloor heating and/or water heating is using such large amounts of water. Is it normal for underfloor heating to use so much water when it is on?

The underfloor heating and hot water are fed from an air source heat pump.

The hot water is held in a 200 litre cylinder next to the underfloor heating manifolds. We do not have any water tank in the loft.

I'm now going to test the modern dual flush toilets to see if they are using water when they shouldn't be. They appear to be dry around the pan and I can't isolate them easily because the shutoff valves for each toilet has been boxed in.

Unfortunately our landlord did not provide us with any instructions for this heating system in this house so I'm having to learn it as I go along.

Thanks,

Chris

 

[John.g]

The heating systems shouldn't use a drop of water, maybe the occasional top up of a few litres every couple of months, it points to a leak on the mains between the stopcock and the house but you could repeat the heating test again say one hour off then repeat with one hour back on, no domestic use for these two hours.

 

[ShaunCorbs]

Any toilets running / overflowing ?

A bit of food dye in the cisterns will tell you if there passing / overflowing

 

[John.g]

"The hot water is held in a 200 litre cylinder next to the underfloor heating manifolds. We do not have any water tank in the loft."
You may have a unvented HW cylinder except that you have a combined HW cylinder and storage tank, if unvented you will have a PRV (pressure relief valve) on the cylinder and probably another one called a expansion valve after the cold water pressure reducing valve to the HW cylinder, both of these will vent into a tundish so ensure especially at night that neither is expelling water, this can happen if you have very high mains pressure and the pressure reducing valve is faulty.

 

[JX350C]

Hi all,

Thank you for all the helpful replies. They are much appreciated.

I unfortunately cannot isolate the toilets because the isolation valves are boxed in behind each toilet. So I was unable to find a way to test them by themselves to see if they are using the 3 or 4 litres per hour that we are losing when the DHW and underfloor heating are off. I can't see any water running down the back of the pan and they both seem to stay dry for both toilets.

So last night I switched on the hot water again to try to work out if the high water usage is being used by the DHW or the underfloor heating or both. I left the underfloor heating off. The DHW was just switched on as auto at the control panel and is only scheduled to come on once at night.

I then took a meter reading this morning and we had used 580 litres of water overnight.

We only used the toilet a few times and we didn't use any baths or showers. We didn't even put the dishwasher or washing machine on.

I have once again switched off the main stopcock in the house and the meter in the street then does not change. I have tested that over several hours and the reading never changes. So there is definitely something in the house using all this water. At the moment the main culprit appears to be the DHW or underfloor heating.

Thanks,

Chris

 

[ShaunCorbs]

Is your heating system sealed eg do you top it up with a filling loop ?

 

[John.g]

When you think of it 580L loss over say 8 hours is "only" 1.2LPM.
If its the UFH then check that the topup system has a auto fill PRV, if so, shut it. If HW and not on the hot side check the cold water inlet tundishes.

 

[EvilDrPorkChop]

When you think of it 580L loss over say 8 hours is "only" 1.2LPM.
If its the UFH then check that the topup system has a auto fill PRV, if so, shut it. If HW and not on the hot side check the cold water inlet tundishes.

If something was leaking at 1.2lpm that would show itself pretty quick - unless of course it's going down a drain

 

[JX350C]

Is your heating system sealed eg do you top it up with a filling loop ?

Unfortunately I don't know enough about this system yet as we were not given any instructions when we moved in so I'm trying to learn as I go along. I'm also just a DIYer.

 

[ShaunCorbs]

Ok do you have a cylinder or just a boiler ?

 

[JX350C]

When you think of it 580L loss over say 8 hours is "only" 1.2LPM.
If its the UFH then check that the topup system has a auto fill PRV, if so, shut it. If HW and not on the hot side check the cold water inlet tundishes.

Thank you. I will try to locate those once I work out what they look like. I will upload some pictures of the install once I have them off the phone. The tank is a Grant HPFR200PPC/BS Monowave Unvented Single Coil Indirect Cylinder with 50 Litre buffer.

 

[JX350C]

If something was leaking at 1.2lpm that would show itself pretty quick - unless of course it's going down a drain

I do see that there is pipework from the cylinder that appears to go into drain plumbing. Near the start of that pipe is what I now know is a tundish. I've learnt something new today. About half way along that pipework is a T join that appears to go into a pressure meter which is in turn connected to the bottom of a large red cylinder. Looking at the tundish there are no drips or running water through it and it is completely dry.

 

[ShaunCorbs]

So sealed system so won’t be heating

Any pictures of the toilets ?

 

[JX350C]

Ok do you have a cylinder or just a boiler ?

I don't have a boiler because we have an air source heat pump that heats the water. The cylinder is a Grant HPFR200PPC/BS Monowave Unvented Single Coil Indirect Cylinder with 50 Litre buffer.

 

[Murdoch]

What does your landlord say about the situation?

 

[JX350C]

What does your landlord say about the situation?

I have actually just spoken to my landlord, who is very supportive, and I've just spoken to his plumber who originally installed the system and he is coming over next week to investigate.

In the meantime I've just got some food colouring so I can take the top off the toilets and test if they are using any water when they shouldn't be.

 

[JX350C]

So the plumber came over today to investigate. All he did was open the manhole outside to see if there was water running and he checked the stopcock in the house was open. There was no water running down the drain outside. He then wanted to see if the meter changed when water was being used. I put a tap on in the house and the meter was changing. He didn't test anything else and instead suggests that the water company come out and test the meter etc. He says that he thinks the meter does not record litres used in the red portion of the meter reading. He said the black portions of the meter are litres. I have been told by the water company that the numbers in the black portion are cubic metres (1000 litres) and that the red portion are litres. I showed him my meter reading records and he seems to think that they are not litres and seems to think there is nothing to worry about. He didn't do any testing of anything in the house and didn't even look at the DHW or heating system. I feel foolish for getting the plumber over and maybe I have been given incorrect information from the water company on how to calculate the water usage. Maybe I have been given incorrect information from the water company but they are saying that we are using 5 times the usage of a normal household. I have just spoken to the water company and they are sending someone out to do some testing.

Does anyone know how to calculate the my actual usage, as I'm now not sure I am doing it correct? My meter has 8 digits on the reading. 5 are in the black and three are in the red to the right hand side of the reading.

Thanks,

Chris

 

[John.g]

Mine looks like what it says on the tin...... so that reading below is 1,234M3, 670litres, if you use say 580 litres then the reading becomes 01235250.

 

[JX350C]

Mine looks like what it says on the tin...... so that reading below is 1,234MS, 670litres, if you use say 580 litres then the reading becomes 01235250.

View attachment 82209

Thanks for that. That is exactly my understanding but the plumber seems to think that is not correct so left me feeling very confused and stupid and was insistent that I was wrong.

I simply subtract the previous meter reading from current reading to get the amount of litres used over that period.

Here is an example of my meter readings over the last week or so:

16/03/2023 09:09​	00478324​	394​
16/03/2023 12:54​	00478432​	108​
16/03/2023 14:03​	00478435​	3​
16/03/2023 15:00​	00478436​	1​
16/03/2023 15:49​	00478461​	25​
16/03/2023 17:32​	00478465​	4​
17/03/2023 10:32​	00479045​	580​
21/03/2023 15:18​	00481909​	2864​

The third column is the difference between the previous meter reading so, if my calculation is correct, should be the number of litres used between the readings. The meter readings with low numbers are when I had the DHW and underfloor heating switched off. So I am convinced this is being caused by either of those. But he didn't even check those and just said that it can't possibly be them.

Thanks,

Chris

 

[John.g]

All present and correct.

Did you try the consumption with the DHW switched off only and then the UFH switched off only.
The UFH should be the easiest to check out, locate the (red) expansion vesse (or vessels) then locate the filling loop, some filling loops have a flexible hose with shut off valves at both ends, ensure both of these shut off and slacken the hose off at both ends to ensure no water passing. Other systems have a auto fill system where a pressure reducing valve set to 1.0bar keeps the system pressed up, this also has a isolating valve before the pressure reducing valve, shut this.
DHW: There should be a isolating lever or gate valve on the cold mains suppy to the cylinder, shut this.

 

[JX350C]

Thanks John. At the moment I've just switched the underfloor heating off by switching off the controllers in each room and ensuring the actuators are closed. When the DHW is switched off I have only changed the mode on the control panel to off instead of in the auto position which manages the DHW on a schedule. I do have the red tank you mention and there is a large blue lever on the cold water mains to the cylinder. I'll try to do what you have suggested and I am now going to also take meter readings every hour, record exactly what we used and then see if the meter readings tally with the actual usage.

Thanks,

Chris

 

[EvilDrPorkChop]

Maybe some photos of the install would help?

 

[John.g]

Thanks John. At the moment I've just switched the underfloor heating off by switching off the controllers in each room and ensuring the actuators are closed. When the DHW is switched off I have only changed the mode on the control panel to off instead of in the auto position which manages the DHW on a schedule. I do have the red tank you mention and there is a large blue lever on the cold water mains to the cylinder. I'll try to do what you have suggested and I am now going to also take meter readings every hour, record exactly what we used and then see if the meter readings tally with the actual usage.

Thanks,

Chris

Re the UFH, You will have to ensure that the make up filling is isolated, it doesn't matter how many controllers or actuators are closed.

 

[JX350C]

Maybe some photos of the install would help?

I managed to get some photos which I will upload for you.

 

[JX350C]

Re the UFH, You will have to ensure that the make up filling is isolated, it doesn't matter how many controllers or actuators are closed.

Thanks John. Understood.

 

[JX350C]

 

[JX350C]

Those are the only photos I have so far. I need to move out our laundry shelving to get pictures of the UFH manifolds and controls and the other pipework. I will try to do that tomorrow and upload them.

Thanks,

Chris

 

[JX350C]

Here are some other photos of the red expansion tank that I have previously taken. I have noticed from these photos that the isolation valves connecting the flex pipe to the cold water feed are in the off position. Should they be in the open position during normal every day use? I haven't noticed this before.

 

[ShaunCorbs]

No you should only open them when you want to refill the heating system by the looks of it you need to

Open one first eg inline with the pipe

Then slowly open the last one until you hear water don’t open it any more watch the pressure guage when it gets just above one shut that valve then shut the other one

 

[JX350C]

No you should only open them when you want to refill the heating system by the looks of it you need to

Open one first eg inline with the pipe

Then slowly open the last one until you hear water don’t open it any more watch the pressure guage when it gets just above one shut that valve then shut the other one

Thanks ShaunCorbs. I will do that.

 

[John.g]

Its probably been months or even a year or so since the last top up so that rules out any part of the heating system as the culprit.

Just to return to the meter, it may be no harm to take a meter reading, then run off some cold water into a 10 or 20 litre drum and note the metered consumption.

 

[JX350C]

Its probably been months or even a year or so since the last top up so that rules out any part of the heating system as the culprit.

Just to return to the meter, it may be no harm to take a meter reading, then run off some cold water into a 10 or 20 litre drum and note the metered consumption.

Thanks John. That is a great idea. I will try that test later today. I am keeping an extended log today and recording meter readings every hour or so and keeping a log of what water we know we used during those times.

 

[plumbingservices]

This is absolutely insane! the underfloor heating controllers should not use this much water.

 

[JX350C]

This is absolutely insane! the underfloor heating controllers should not use this much water.

I agree. The amount of water we are using is insane and something is using water somewhere even when we seem to have things switched off. I've been logging every time we use water and what we used and then taking meter readings roughly every hour to see if the estimated usage matches the meter readings. At the moment I haven't been able to work out exactly what is causing this water usage. Tomorrow I am going to start isolating the DHW, Underfloor heating, showers, toilets (although those are boxed in so I cannot access their isolation valves) to see if I see a drop in usage.

 

[ShaunCorbs]

It’s not the ufh / heating as it’s sealed and won’t refill