K
Welcome to the forum. Although you can post in any forum, the USA forum is here in case of local regs or laws
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diamondgas
The fact that it does expand means it will require somewhere to expand hence the need for something to take up the expansion ... It may only be a thimble full but if there's nowhere for it to expand into there's a chance it'll pop something or other! The cold water entering a property takes up the heat of the house and thus expands ... Boiler manufacturers knew about this way back when combi's first came on the market and would come with a mini arrestor fitted as standard.
Interesting one. Personally I think an EV would be overkill although wouldn't hurt except the extra expense. Most houses are metered these day and they all have c/v in as far as i'm aware. Never related any problems to this other than thermal effects from a combi boiler which normally specify a c/v before e/v. My understanding of this was to reduce any possibility of cross contamination of hot or partially heated water expanding back to a point where it could be drawn off via a cold tap?
Also if the cold main can take 6+ bar static then surely 3bar plus expansion wouldn't increase beyond this, although would be interested to see the sums.
Also if the cold main can take 6+ bar static then surely 3bar plus expansion wouldn't increase beyond this, although would be interested to see the sums.
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diamondgas
Have you ever watched a pressure gauge on a combi when the EV has lost its charge? Rapid rise in build up of pressure within a very short period of time! Water is virtually none compressible so any expansion will raise the pressure in pipework if there's no means provided for the water to expand into.
Yes I know what you mean DG, but water expands at a higher rate the hotter it gets 4oc being where it is most dense.
4-21oC I make that about 0.5% increase in volume. So say as an example a house contain's 30 mtrs of 15mm cold water main x 0.145ltrs = 4.35ltrs + 0.5% (0.02175) = 4.37 ltrs
I'm stuck here for a minute, i'd like to try and equate that into a pressure rise! (as I have nothing better to do with my time at the moment)
Not saying who's right or wrong, genuinely interested in this.
4-21oC I make that about 0.5% increase in volume. So say as an example a house contain's 30 mtrs of 15mm cold water main x 0.145ltrs = 4.35ltrs + 0.5% (0.02175) = 4.37 ltrs
I'm stuck here for a minute, i'd like to try and equate that into a pressure rise! (as I have nothing better to do with my time at the moment)
Not saying who's right or wrong, genuinely interested in this.
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diamondgas
I like the sums 🙂 With your example are you saying there'll be an increase in volume of 20ml? 4 doses of medicine 🙂 It has to go somewhere though yeh? Maybe the pipework expands .... thing is with every replenishment of cold water the pipework will expand again and again ... 🙂 There's something stuck in my memmory banks that says that an arrestor type ev needs to be fitted if a check valve is fitted to the mains...!
Many thanks sambotc for the research ,
I went to bed thinking if Bends pulled in copper ,
were oval enough to work like the bent thin tube pressure guages
that straighen out as pressure rises .
were oval enough to work like the bent thin tube pressure guages
that straighen out as pressure rises .
Keen test would be hydraulic ... but you can get too interested ,
and the work just don't get done !
(Like Quantum stuff ,a pressure guage would change the pressure !)
and the work just don't get done !
(Like Quantum stuff ,a pressure guage would change the pressure !)
so why do unvented water heaters say that an EV is not required when there is say 1.5m of distance between the heater and the nearest cold water draw off, this is deemed sufficient space for expansion, i would only imagine an EV would have to be fitted if there was a CV or PRV on the cold inlet to the boiler
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diamondgas
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diamondgas
glad we are all in the same boat then! I understand it in principle but couldn't get the sums to work as they described, it looked to me as if the example they used was incorrect!
thinking about it, I can't see why a pressure reducing valve would be any different to a check valve in principle, but the water board haven't been fitting E/v after fitting a meter, and surely if anyone was going to see the brunt of an issue like this, they would? I'd imagine after a couple of systems popped due to check valves in the water meters, they'd be right on the case?
thinking about it, I can't see why a pressure reducing valve would be any different to a check valve in principle, but the water board haven't been fitting E/v after fitting a meter, and surely if anyone was going to see the brunt of an issue like this, they would? I'd imagine after a couple of systems popped due to check valves in the water meters, they'd be right on the case?
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diamondgas
You're dead right sambotc ... Maybe my old grey matter is messing with me and I got it wrong 🙂 Worth the investigation though and getting the cogs spinning a bit 🙂 Cheers 🙂
K
kay-jay
Just an after thought. But what other position would a 1litre ev be used in? They make em.
so there must be a use for em and i was told they were fir cold mains on pipework between checks and prv or fixed jumper stop taps because expansion can't be taken up in any direction.....
Sent from my GT-I9100 using Tapatalk 2
so there must be a use for em and i was told they were fir cold mains on pipework between checks and prv or fixed jumper stop taps because expansion can't be taken up in any direction.....
Sent from my GT-I9100 using Tapatalk 2
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