Combi boiler and cold water tank in loft??

clarac

Hi, can anyone help me please!?

We have just moved into a new house and have gotten someone to gut the bathroom upstairs. The main reason was for a new more powerful shower however it is all finished and the shower is less powerful than the previous old electric shower there was?

We have a combi boiler and the idea was to run the new shower off this for more power.

We have now realised there is a huge cold water tank in the loft that seems to be feeding the house with cold water and i have just been told that the tank is actually filthy and we shouldn't be drinking/cooking or brushing teeth with any of our cold water!!!

Has anyone heard of this? Should we even still have a cold water tank if there is a combi boiler?

We are of the impression that the tank is not needed if there is a combi boiler.

What can we do?

Thanks in advance - ANY help appreciated!

System

hot water comes from a combi boiler, cold comes from the tank...
quite common

i was previously advised against having a shower running off the combi as the pressure wasn't good enough, guess it depends on the individual boiler....

jamesperrett

clarac wrote: »

we shouldn't be drinking/cooking or brushing teeth with any of our cold water!!!

In a traditional system your kitchen tap will be fed direct from the incoming water supply while the rest of the cold taps are fed from the tank in the loft. You should be using the kitchen tap for drinking water and bathroom taps mainly for washing.

James.

WestonDave

Try running each tap in turn and whilst each is on check the tank in the loft - if the water level drops and it starts to refill, then the tap which is on is fed by the tank. If it doesn't then the tap is mains fed. Similiarly with flushing toilets etc.

keystone

When a combi boiler is fitted its usual to remove the cold water storage tank in the roofspace and the hot water cylinder (usually in the airing cupboard). The primary purpose of the CWST is to replenish the HWC as hot water is drawn off.

The combi (fed by mains cold) heats hot water on an "on demand" basis so storage is no longer required. Normally all cold taps are converted to mains supply when a combi is fitted so storage is no longer required.

So what you describe is unusual although perhaps not unique but it might be as well to ensure that a) the boiler is, indeed, a combi rather than a condensing system boiler and b) that the CWST actually is still functional rather than just abandoned and negligently, left full of water.

So:

1. Do you still have a cylinder in the airing cupboard and does it still supply the hot taps?

2. If not when you run a hot tap does the boiler instantly fire up to provide heat.

3. When you run a cold tap (except in the kitchen which will almost certainly be mains) does the CWST start to fill up as water is drawn off?

4. What is the make / model of the boiler?

Cheers

keystone

the_r_sole wrote: »

hot water comes from a combi boiler, cold comes from the tank...

If hot water is coming from a combi and cold from a tank then shower supplies are hoplessly imbalanced and it won't work properly.

I was previously advised against having a shower running off the combi as the pressure wasn't good enough, guess it depends on the individual boiler....

Its not a question of pressure its a question of flow rate @ 35degC rise that the combi can provide. If a shower is to be fed then the combi should be spec'd appropriately in the first instance.

Cheers

clarac

Hi!

Thank you so so much to all of you for your speedy and helpful replies!

When hubby comes home i will ask him to check cold water tank in the loft when i run the kitchen tap just to see where the cold water supply is coming from for the kitchen (the word rancid was used for the cold water tank - yeuch!!)

The GREAT news is that the old connection for the previous electric shower has been found and connected to the new shower which was already connected to the combi boiler - HURRAH!! Thank you Andrew B you were right.

Keystone - i will get hubby to look at your thread and see what is what with things - Thank you!

a HUGE thank you to all of you and your knowledge!

Really appreciated!

sgoode

We had this in our house when we moved in. A combi boiler had been recently installed yet the old manky cold water tank remained in the roof. As someone previously mentioned having a shower (with mixer tap) was completely hopeless as there was no cold pressure compared to the hot. The surveyor and plumber couldn't work out why it had been left in this way. The plumber even said that the overpowering hot pressure could potentially backfil the tank when using ther mixer tap. We had the tank promptly removed and the cold hooked up to the mains. The difference was unbelievable, especially when having showers. The toilet cisterns now fill in a fraction of the time and the water in the bathroom is safer to drink. It was cheap to rectify as well.

Hope this helps.

googler

sgoode wrote: »

We had the tank promptly removed and the cold hooked up to the mains. The difference was unbelievable, especially when having showers. The toilet cisterns now fill in a fraction of the time and the water in the bathroom is safer to drink. It was cheap to rectify as well.

If the water supply is cut off for any reason, and the water board can't rectify it within a few days, and your neighbours don't have a supply either. how will you flush your toilets?

That's what I thought every house needed a CWST for......

googler

andrew-b wrote: »

Somewhere along the way this got forgotten about though with the introduction of combis!

..and I thought it was HW tanks that got removed when Combi got installed.....

skins1979

sgoode wrote: »

We had this in our house when we moved in. A combi boiler had been recently installed yet the old manky cold water tank remained in the roof. As someone previously mentioned having a shower (with mixer tap) was completely hopeless as there was no cold pressure compared to the hot. The surveyor and plumber couldn't work out why it had been left in this way. The plumber even said that the overpowering hot pressure could potentially backfil the tank when using ther mixer tap. We had the tank promptly removed and the cold hooked up to the mains. The difference was unbelievable, especially when having showers. The toilet cisterns now fill in a fraction of the time and the water in the bathroom is safer to drink. It was cheap to rectify as well.

Hope this helps.

Hi sgoode,

We have exactly the same issue in our new house. Who did you get to rectify the situation? A plumber? How much did it cost (if you don't mind me asking) and was the work destructive?
Thanks
Simon