Separate water tanks?

[evdama]

I have a (really) hard water supply(a kettle will fur up in a matter of weeks) electrically pumped up in blue plastic 25mm from the borehole via a floatswitch

Im having a new boiler soon and was advised to get a filter on the incoming supply.
I was thinking of the two stage phosphate filter system, as seen in the SF catalogue.

As the water and expansion tanks are old, scabby,and full of dead creatures,Im going to replace them pdq.
However looking at the data sheet for the filter it suggests that you shouldnt put it on the drinking water pipes.

Could someone have a pick at this idea:
Im aware that linked tanks are frowned upon but....
A new 25 gallon tank with the floatswitch in it, feeding the domestic cold water system only,with local electolytic scale inhibitors on the washing machine outlet and the cold kitchen tap.
This tank then feeds the two stage filter via a check valve to another new 25 gallon tank which supplys the domestic hot water system.
Therefore any phosphated water finding its way back up the vent pipe from the h/w cylinder wont contaminate the cold water supply.
Will the 2 stage filter work under such low pressure?
Finally, the boilers new 4 gallon F/E tank is fed via a checkvalve and floatvalve from this intermediate hot water supply tank Phosphated water will be ok for the boiler?
Eack tank has its own overflow.
Each downstream tank is isolated from its parent(s).
Can the two 25 gallon tanks be at the same floor level?
The hot supply tank connector should be artificially higher than normal ?
What have I missed?

 

[Agile]

You don't seem to be having much professional assistance with the design of your system.

You choice of boiler may be relevant and if your water really were that hard it could be better to fill the system with bought in deionised water.

But I am not sure that your water really is all that hard compared with parts of Berkshire where it is far harder than London but even there with properly operating combi boilers fitted with the appropriate protection they all work fine if there are no faults like dripping taps. Many don't have any kind of scale reduction devices but still work fine although all manufacturers now advise them for a combi.

In your case, I would advise an electrolytic water treatment device on the input to your loft tank(s) and nothing else. The water from these is suitable for drinking. You only need one tank.

I don't think it would be needed but you could also have a polyphosphate scale reducing unit on the feed to the hot water cylinder only. But I would not advise that. The polyphosphate treatment does result in precipitated lime compounds in the drains which can be a nuisence.

Presumably you don't have any scale reducing device at the moment?

If you wanted to spend more money and have ongoing salt costs you could install a water conditioner. But they are all designed to be fitted on mains pressurised supplies so not really suitable for your situation. I like the Harvey as they are a very on the ball company and their units are water powered so don't need an electricity connection.

Tony

 

[Agile]

Properly fitted nothing wrong with linked tanks. Often needed when small loft hatch. Or a greater capacity is required.

But they do cause problems and all in my experience as a result of careless installation. They should never be linked by close coupling because afterwards those connections are not reachable from outside.

Tony

 

[bernardgreen]

They should never be linked by close coupling

If height permits then having one tank above the other with supply pumped up to the higher tank and the lower tank supplied from the higher tank via a low pressure ball valve can be beneficial.

There can be two ( or more ) tanks at the lower level each with it own ball valve. One for general cold water and one for the heating system ( radiator header tank ).

When supplied from a bore hole or well the upper tank provides drinking water without risk of pollution from the other tanks. The upper tank can be small volume which reduces the amount of stagnant water and hence reduces the risks of bacterial growth in the drinking water supply.