Combi boiler - no storage tank

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If, as the manufacturers say, with a combi boiler you do not need a cold water storage tank in the attic to feed it, is it worth eliminating the storage tank altogether and feed the cold water for taps, etc directly from the mains? or is there a benefit in having a tank anyway?
 
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Get rid of it and have all colds on mains. This will balance the hot and cold supply's and give fresh clean water to each tap.
 
The only benefit to having a tank is if you ever have your water cut-off you'll always have that "tank" of water in the loft.... But how often is that? Once in 6 years or so for a day? Hmmmmm....

Think I'd agree with gas4you on this one 100%




BTW; don't forget you may need to update the cistern(s) on you toilet(s) if you are swapping to 100% mains fed as some cisterns are low-water pressure types and are only designed to be fed with tank-fed systems.... Doesn't cost much at all and well worth it.
 
One further question. If I decide to do away with the water tank, but the rising mains pipe has been installed going to the attic first. is it possible to go up to the attic first, and reach the parts of the house that need the cold water feed through it and descend to the various points, in such a way that the rising mains tursn into "descending" mains?
 
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You can do.... Lots of people do; although personally I try to keep my piperuns short where possible and would much rather consider coupling up elswhere; then decomission the pipework that's not needed entirely.
 
While you are at it, check the run of the hot water pipe.
At my son's house we found the hot from the combi had been routed to where the old hot tank was in the back bedroom, to connect to the original hot circuit. Result was a very long hot run - hot water took ages to get to the bathroom.
 
If you wanted to do everything in the best possible way than I would say keep the cold cistern to supply all WCs and all washbasins. In fact everything except the cold supplying any showers where you need a balanced pressure supply.

Doing that will ensure that the mains water supply is used most efficiently and any wc flushing or cold at a washbasin will not affect the critical hot water flow through the combi.

That however often means several extra pipes and few plumbers would bother unless the householder specifically asked for it. A DIYer could consider it though!

Its what I do at home though!

tony
 
Agile said:
If you wanted to do everything in the best possible way than I would say keep the cold cistern to supply all WCs and all washbasins. In fact everything except the cold supplying any showers where you need a balanced pressure supply.

Doing that will ensure that the mains water supply is used most efficiently and any wc flushing or cold at a washbasin will not affect the critical hot water flow through the combi.

Until the cold tank level lowers enough to give full cold water flow throw the ball cocks and you are back to stage one. Unless you sized the tank to suit an restict the flow through the cold tank ball cock.
 
Agile said:
If you wanted to do everything in the best possible way than I would say keep the cold cistern to supply all WCs and all washbasins. In fact everything except the cold supplying any showers where you need a balanced pressure supply.

Doing that will ensure that the mains water supply is used most efficiently and any wc flushing or cold at a washbasin will not affect the critical hot water flow through the combi.

That however often means several extra pipes and few plumbers would bother unless the householder specifically asked for it. A DIYer could consider it though!

Its what I do at home though!

Which means no mixers as the hot and cold are unbalanced. Having two individual taps. A real silly idea.
 
Doctor Drivel said:
Agile said:
I would say keep the cold cistern to supply all WCs and all washbasins. In fact everything except the cold supplying any showers where you need a balanced pressure supply.

Which means no mixers as the hot and cold are unbalanced. I have two individual taps. A real silly idea.


You have not read what I have said!

I have said tank feed everything EXCEPT the showers!

Tony
 
Yes, Tony

I can see your logic, but would rather be brushing my gnashers in fresh water rather than the tepid stuff sitting in an open vented tank in the loft.....
 
Agile said:
You have not read what I have said!

I have said tank feed everything EXCEPT the showers!

Even the combi? That then, needs pump. If main DHW via a combi and cold via a tank there will be a pressure imbalance.
 
any wc flushing or cold at a washbasin will not affect the critical hot water flow through the combi.

Would'nt the hot flow still be affected as the cistern is refilling off the mains. :?: ;)
 
Went to a job a couple of years ago - elderly tenant was complaining of high shower temperatures and feeling very ill.

Over several months several "plumbers" had been sent by the estate agents to sort out this problem. The tenant had been to her GP as she felt so unwell (and looked it :( )

As soon as she opened the front door I could smell the problem. :eek:

Typical bodged combi installation - cold taps had all been left on the tank supply. Unbalanced shower pressures (and no check valves) led to scalding hot water. The cold cistern was located in the bathroom in a cupboard just above the WC so very low static head.

When using the shower mixer hot water would backflow into the cistern resulting in warm stored water and the warning pipe running.

Worst bit was the flat upstairs had diy'ed their new bathroom. The pushfit joints from the bath waste were leaking a significant quantity of waste water through the floorboards into the tenants open tank.

Stored warm stagnant bath water to bathe and wash your teeth in - not surpising she was ill. Its shamefull that so many had missed such a simple problem - one even told her it was just the drains smelling.
 

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