ACV or unvented? What specs? And other recommendations

[Dan Robinson]

Contractor will be in for a big surprise if he doesn't fill it correctly too

 

[Roger928]

They say the dhw tank should be filled and pressurised first from looking at my old manual. Unless the design has changed.
But you would still have situations where its just filled. If the mains was off and a tap is opened!

 

[Mechanical Matt]

If you have a little more space, can you squeeze the ACV SLE PLUS 210? This has multiple connections for UFH and rads. I install many ACV units and have had a 210 running 3 showers no problem.
ACV sell a 6kw, 1 phase immersion if you want decent CH & HW backup too (£95). Once you've connected all the emitter circuits hopefully you'll have a spare connection to have HW priority with zone valve supplied.

Just an idea.

 

[Roger928]

Have you ever filled the CH circuit first?
Will the center tank be crushed?

 

[Mechanical Matt]

Nope and wouldn't risk it. Manu does say 'Do not' in the book.

 

[Roger928]

What happens when the mains is turned off and no pressure in the inner tank? Obviously not much. And a likely scenario.
Unless the CH happened to be close to 3 bar?
Will ACV stand over them if it collapsed in that scenario?

 

[Mechanical Matt]

Whenever I've needed to drain the HW I've drained the outer tank too.

 

[Dan Robinson]

What happens when the mains is turned off and no pressure in the inner tank? Obviously not much. And a likely scenario.
Unless the CH happened to be close to 3 bar?
Will ACV stand over them if it collapsed in that scenario?

Water, not being meaningfully compressible, probably won't collapse the secondary side unless the primary was very close to 3 bar.


Interesting question though.

 

[Roger928]

Whenever I've needed to drain the HW I've drained the outer tank too.

But what do you think happens when the mains pressure is turned off and 3 bar in the CH side?
Lets say the plumber is there to change a tap. Have you ever asked ACV technical that?

 

[Dan Robinson]

Lets say the plumber is there to change a tap.

You'd hope local service valves would be in place

 

[Roger928]

The inner tank being corrugated has to be quite strong.

 

[Dan Robinson]

I've got half a dozen I look after, and only one I've installed first hand....

That has had the site plumber turning off the supply dozens of times over the last 2 years or so with no problems.

Just waiting to see what the client says in reply to the notification that the £5k water treatment device spec'd by the consultant needs an ANNUAL service at nearly £700.

Im pretty sure it was suggested over my salt softener on the grounds it was maintenance free


Oh dear.

 

[gdis]

Many thanks to all of you for the many replies. Particularly for those more intelligible for me and to my point.

So, if I interpret you guys correctly, the consensus seems to be:
1) Yes, go for an ACV because of the quicker recovery time
2) If possible have an ACV SLE PLUS 210 installed (I think it would fit, Mechanical Matt)
3) Have HW priority
4) Choose a dual input boiler to help efficiency
5) Have a 6kw, 1 phase immersion heater

A few more questions, if I may:
a. I have found a Smartline SLE Plus here and a Smartline E 210 plus – are they the same thing?
b. Any recommendations for a dual input boiler?
c. Builder suggests a 28 Kwh boiler would do the job; does it sound reasonable to you?
d. Immersion heater – ACV talks about a 3Kw; would it be a problem to upgrade it? And is there any downside to using it in summer mode either than the lower efficiency?

 

[St0rmer66]

Immersion heater is just a backup. 99% of people do fine with 3kw. Up to you if the extra reheat time is that big of a deal when you'll only use it a few times ever, if at all.

 

[Dan Robinson]

The 6 kw immersion was referenced as the ACV mentioned is a supply for the heating.

Frankly it is very ott IMO. A system based on the one I pictured is far more practical and cost-effective. Intergas boiler with a Joule cylinder. Size the boiler to the buildings Heat loss. 28kw is probably too much.