Hot Water Tanks

maskerade

We've just bought a house that has a combi boiler and hot water tank. I've not seen this before but the family who lived there before us was far bigger than ours so I guess it was to ensure sufficient hot water for them all. 

Ideally I'd like to get rid of the tank so i can use the cupboard for something else. It's just me and my husband and we had no issues with just a combi boiler in our last place. In my head I also think storing hot water in a tank is more expensive than just having it on demand from a combi boiler - is that right or have I made that up?

I intend asking a Gas Safe plumber to advise on whether the combi boiler could meet our needs without the tank but before I do I thought I'd like to ask if my thinking around the cost of running a hot water tank is right so I am asking the right questions and not sounding too silly!

Thank you in advance. After five years being a tenant having to do our own maintenance again is rather a shock!

McKneff

You wouldn't need to run it. You would only turn it in to heat water if you combine broke down 
We have a Spare tank but it is only used when our normal system breaks down. It has an immersion heater in it but in 8 years it's never been used. 
If you need the room for something else I would get rid. 

ThisIsWeird

Hi maskerade.

As McK says, you shouldn't have to heat the hot cylinder if you didn't want to.

Thanks an interesting 'combo' - a combi and a hot cylinder! It can be done - the CH output of the boiler is diverted for use to heat a cylinder, just like a normal system boiler. But, it's unusual. So I wonder if the hot cylinder is only heated via an electrical immersion?

We could do with photos of your boiler, its make and model. And ditto of the cylinder, showing all the controls and valves it may have around it. If it has an info plate on it, then the make and model on there would be good too. Oh, and photos of your controls - the timer/programmer and stuff.

Q - is the cylinder 'hot'? Does it contain hot water?

Q - when you turn on the kitchen hot tap, does the combi boiler fire up right away, remain on as long as the tap is running, and go off when the tap is closed? If 'yes', then what happens when you turn on other hot taps, or run a shower?

Q - what is the flow from the hot kitchen tap like? Gushin'?

Section62

maskerade said:

We've just bought a house that has a combi boiler and hot water tank. I've not seen this before but the family who lived there before us was far bigger than ours so I guess it was to ensure sufficient hot water for them all.

Another reason might be if the mains water pressure/flow is not sufficient for the whole house. A traditional system with a cold water tank in the loft feeding a hot water cylinder is a good way of overcoming issues with pressure/flow from the mains.

The question is, does your hot water tank get fed from a tank in the loft, or is it connected directly to the mains?

maskerade said:

In my head I also think storing hot water in a tank is more expensive than just having it on demand from a combi boiler - is that right or have I made that up?

It depends on your circumstances.  Some people will claim a gas combi is always the cheapest way of heating hot water, but this isn't always the case.  In particular, if you have solar panels or a very cheap electric rate, the cost of using an immersion heater in the hot water cylinder may be favourably comparable to a gas combi.

A well insulated hot water cylinder doesn't lose as much heat as some people imagine - and if the tank is in an airing cupboard then the lost heat can be put to some use before it escapes into the house.

However, the more important issue is whether you have the mains pressure/flow to make a combi suitable - if you don't and you start using a booster pump to overcome this then the maths changes.

maskerade said:

...but before I do I thought I'd like to ask if my thinking around the cost of running a hot water tank is right so I am asking the right questions and not sounding too silly!

Again, it depends on the circumstances.  You first need to understand whether the hot water tank is mains fed or fed from a tank in the loft.  You also need to think about how you use water through the day.

Also bear in mind that the supposed cheapness of gas combi hot water heating has in the past been based on cheap gas compared to the cost of electricity.  The government have signalled that over the longer term the cost of gas needs to go up relative to the cost of electricity.  Using electricity during the day is more expensive than during the night.  So it follows that at some point in the future, the cost of heating water using a gas combi may become more expensive than using an immersion heater off-peak.  The ability to store hot water isn't something to get rid of without careful thought about the future.

Section62

ThisIsWeird said:

As McK says, you shouldn't have to heat the hot cylinder if you didn't want to.

It depends how the house has been plumbed - one possibility is the kitchen tap is off the combi, but all other hot water points come from the HWC.

Grenage

As section says, there is probably a reason the tank exists.  It could simply be for an awesome power shower, or it could be poor pressure.

We have a large hot water tank; we don't really need it, but we have a power shower and I'll soon be using an immersion heater to store solar surplus.

ThisIsWeird

Section62 said:

ThisIsWeird said:

As McK says, you shouldn't have to heat the hot cylinder if you didn't want to.

It depends how the house has been plumbed - one possibility is the kitchen tap is off the combi, but all other hot water points come from the HWC.

Absolutely - hence the Qs I asked of the OP :-)

twopenny

I know I was glad of my electric immersion when my boiler died just before the Beast  from the East. No heating I didn't want a shower in a freezing bathroom but a hot bath.
Neighbours whose combi exit froze didn't have anything for some time as plumbers were busy or snowed in.

BUFF

I would also mention that the next replacement cycle for the heating system will probably involve a heatpump & that will require a tank for stored hot water. Seems daft to pay to take one out  & then pay to put one back ...

FreeBear

BUFF said:

I would also mention that the next replacement cycle for the heating system will probably involve a heatpump & that will require a tank for stored hot water. Seems daft to pay to take one out  & then pay to put one back ...

Depends on how old the current tank is.

If it anything like mine, installed around 1970, imperial fittings, and uninsulated, a new one may well be preferable. The heating coil might not be compatible with a heat pump, so a new cyclinder would have to be fitted if that were the case.

BUFF

Possibly, yes, but you would not/should not remove & replace the pipe runs.