advice on two HW cyclinder set-up.

[mellie_man]

Hi

Refitting main bathroom and adding power shower (with body jets). Second bathroom (for the kids) already has a powered shower, so am upgrading existing pump to run both rooms (as existing pump is old and noisy anyway).

Here is a pic. Fitting new salamander ESP 100 and they state dedicated HW supply from surrey or essex flange. I know I should follow MI but presume this will mean fitting two of said fixing and drawing off a joining pipe. Was hoping to just draw off existing Tee (upgraded to 22mm) before reading the small print.

Any hope of not increasing the amount of work...

Untitled

• mellie_man
• 6 May 2011
• 1

Untitled

• mellie_man
• 6 May 2011
• 1

tanks have separate CW feeds and there are two outlets, one you can see leading down from the white painted 45deg vent pipe, the other is off the back of the criss cross of pipes that link the top of the two tanks. current pump source Tee to white 15mm plastic.

 

[Agile]

Why do you think the flow from each cyl will be exactly the same so they both run cold together?

Why do you think they will reheat at the same speed ?

Thats not the way that I would have done it!

Tony

 

[mellie_man]

No it's not the way I would do it either, but thats whats there, so unless I spend the time and money to replace the whole thing thats what I've got to work with. The set up was like that when we moved in and has not caused any problems in 4yrs. (same heating loop runs through both tanks and tank stat is on the tank second in the loop). If I were to replace it I would put one tall tank in.

 

[muggles]

If you don't install it according to the instructions you'll invalidate the warranty

 

[commercialman]

 

[CharteredEngineer]

I think you'll draw off the one on the left much faster than the one on the right, especially if you put a massive pump on it.

are they indirect cylinders? in which case how is the coil set up?

 

[mellie_man]

Having checked again the tank coils are linked in parallel (flow split to both tanks, outlets join to one return).


CE why do you think Left will draw faster (because the connection is closer!?)
Its hard so see in photo but there is a sort of double loop, so both top outlets are joined in two places (I suppose in an attempt to equalise pressures)

 

[mellie_man]

currently I think the HW Cylinders are both 1050x400 SO to replace and do properly I would need..!?

to run 2 bathrooms both with powershowers

HW 210L
CW 80 Gal

to allow for expansion for later additional en-suite
HW 250L
CW 100Gal (biggest CW tank I can find that might fit into space available)

What sort of HW cylinder could I use as usual indirect sizes only go to 160L (as far as I can find from quick search , presumably why previously 2nd tank was added. Plenty of height for HW cycinder (up to 2m).

AHH found these in interweb anyone used them
https://www.discountedheating.co.uk..._Insulated_Vented_Cylinder_G3_-_Indirect.html

 

[CharteredEngineer]

If you are teeing where the isolator is then there is only one elbow on the left hand side tank, there are a few more on the right hand side. Roughly speaking (and there are various schools of thought), one elbow is about 0.3 to 0.5m of straight pipework. Water like most things will always take the easiest route, you may need some sort of valve to balance it up and get even flow.

My suggestion would be to purchase an unvented steel cylinder in the capacity that you require (300L?) but run it with your current gravity fed tank. I would avoid megaflo and get something with an external pressure vessel eg. santon. When running in gravity you won't need the external pressure vessel but should you upgrade in the future then its much easier to upgrade.

Hope that helps.

 

[mellie_man]

Thanks.
We did look into unvented system when we upgraded boiler a couple of years ago (most plumbers said leave the tanks as the are, but the one that suggested new unvented cylinder quoted £16000 - got the boiler and controls upgraded and relocated for £4000 to which I added wetUFH in remodelled kitchen).

Main CW is 15mm from the point of entry and the house is three stories, so I don't think the pressure would be there. More tempted to fit a 300L solar tank for possible future upgrade (is it possible to fit normal coil to both parts to enable faster heat time?)

Alternately (cheaper)'lift' existing pipework and fit surrey flange to top of both existing cylinders and ensure new Tee off is in the middle of pipe between flanges.

 

[Agile]

Faced with solving that existing installation then I would fit full bore valves on the output of each cylinder and use them to balance the draw off rates.

Then I would fit a notor valve and thermostat to each cylinder's heating coil so they both reheat independently.

They it would work as well as a single cylinder, possibly better if the reheat power was higher between the two.

Tony Glazier

 

[commercialman]

My suggestion would be to purchase an unvented steel cylinder in the capacity that you require (300L?) but run it with your current gravity fed tank.

A little odd to say the least , where would you suggest hot supply to shower pump is connected? , a little difficult trying to cut an essex/surrey flange into an unvented cylinder.

 

[Agile]

As a chartered engineer I am sure that he only reads specification sheets and does not get his hands dirty doing actual practical work!

 

[mellie_man]

Faced with solving that existing installation then I would fit full bore valves on the output of each cylinder and use them to balance the draw off rates.

I would get a pro in for that as I wouldn't know how, but cheaper than replacing cylinder.

Then I would fit a notor valve and thermostat to each cylinder's heating coil so they both reheat independently.

would have been a good idea when the boiler was replaced, but the boiler is in the cellar and the tanks are on the 2nd floor. Wife would not be happy about uprooting the whole house (coil flow/return are only split at the tanks).

 

[Agile]

To fit two motor valves only requires draining the heating circuit to the floor level on the floor with the tanks for a few minutes before refilling it.

Two hours for a DIYer and one hour for a pro.

The wiring and thermostat will take longer and will either need a control cable to the boiler or if thats difficult a wireless link can be used.

Tony