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"Andy Hall" wrote in message ... On Tue, 19 Oct 2004 22:05:42 +0100, "JJJ" wrote: "Colin Wilson" wrote in message et... If I can get my sealed system up to at least 1.5bar by filling it from the mains filling loop, does this mean I have enough pressure to fit a combi boiler? What kind of flow do you get from your taps in litres per minute ? 9 litres a minute from the kitchen tap (the rest are off the cold water tank) Then the answer is that the results will be disappointing. You could look at getting the supply improved or perhaps the stop tap is partly closed. This is the lowest legal minimum for a water supply. Generally for a mains fed system, you need at least 20lpm. If you must use a combi because you would like to get rid of the HW cylinder, then look at one that will accept its water feed from a roof tank. Check that if you have a stopcock or isolation valve/tap in the line that it is fully open. My initial flow rates were rather disappointing until I realised that the combi was fed from an isolation tap, which was only cracked open halfway. Andy. |
more boiler questions.. mains pressure this time.
If I can get my sealed system up to at least 1.5bar by filling it from the
mains filling loop, does this mean I have enough pressure to fit a combi boiler? Jim |
If I can get my sealed system up to at least 1.5bar by filling it from the
mains filling loop, does this mean I have enough pressure to fit a combi boiler? What kind of flow do you get from your taps in litres per minute ? -- Please add "[newsgroup]" in the subject of any personal replies via email --- My new email address has "ngspamtrap" & @btinternet.com in it ;-) --- |
"Colin Wilson" wrote in message
t... If I can get my sealed system up to at least 1.5bar by filling it from the mains filling loop, does this mean I have enough pressure to fit a combi boiler? What kind of flow do you get from your taps in litres per minute ? 9 litres a minute from the kitchen tap (the rest are off the cold water tank) |
In an earlier contribution to this discussion,
JJJ wrote: If I can get my sealed system up to at least 1.5bar by filling it from the mains filling loop, does this mean I have enough pressure to fit a combi boiler? Jim No! It simply tells you that you have a *static* pressure of at least 1.5bar. It tells you nothing about the *flow rate* which your mains supply can sustain. I think the pundits say that you need about 20 litres per minute. -- Cheers, Set Square ______ Please reply to newsgroup. Reply address is invalid. |
On Tue, 19 Oct 2004 22:05:42 +0100, "JJJ" wrote:
"Colin Wilson" wrote in message et... If I can get my sealed system up to at least 1.5bar by filling it from the mains filling loop, does this mean I have enough pressure to fit a combi boiler? What kind of flow do you get from your taps in litres per minute ? 9 litres a minute from the kitchen tap (the rest are off the cold water tank) Then the answer is that the results will be disappointing. You could look at getting the supply improved or perhaps the stop tap is partly closed. This is the lowest legal minimum for a water supply. Generally for a mains fed system, you need at least 20lpm. If you must use a combi because you would like to get rid of the HW cylinder, then look at one that will accept its water feed from a roof tank. ..andy To email, substitute .nospam with .gl |
"andrewpreece" wrote in message
... "Andy Hall" wrote in message ... On Tue, 19 Oct 2004 22:05:42 +0100, "JJJ" wrote: "Colin Wilson" wrote in message et... If I can get my sealed system up to at least 1.5bar by filling it from the mains filling loop, does this mean I have enough pressure to fit a combi boiler? What kind of flow do you get from your taps in litres per minute ? 9 litres a minute from the kitchen tap (the rest are off the cold water tank) Then the answer is that the results will be disappointing. You could look at getting the supply improved or perhaps the stop tap is partly closed. This is the lowest legal minimum for a water supply. Generally for a mains fed system, you need at least 20lpm. If you must use a combi because you would like to get rid of the HW cylinder, then look at one that will accept its water feed from a roof tank. Check that if you have a stopcock or isolation valve/tap in the line that it is fully open. My initial flow rates were rather disappointing until I realised that the combi was fed from an isolation tap, which was only cracked open halfway. Andy. will do. thanks, Jim |
If I can get my sealed system up to at least 1.5bar by filling it from the
mains filling loop, does this mean I have enough pressure to fit a combi boiler? Yes it does. 1.5 bar is easily enough for a combi boiler. However, it doesn't tell you if the flow rate is good enough. Flow rate is more important than the pressure. You mention 9 lpm elsewhere, which is not enough flow rate. However, this poor flow rate might be for a fixable reason, such as a broken/partially closed stopcock, or a modern styled tap with very narrow waterways that is not designed to pass more than that flow rate. (I'm not suggesting that the tap would need replacing, just that it might affect the feasibility test). If you have a garden tap, try measuring the flow rate off that instead. Christian. |
andrewpreece wrote:
Check that if you have a stopcock or isolation valve/tap in the line that it is fully open. My initial flow rates were rather disappointing until I realised that the combi was fed from an isolation tap, which was only cracked open halfway. Some combis control the flow rate of hot water produced, some dont. Hence in winter (i.e. cold incoming water), the ones with control will produce water at the same temperature as before, but a lower flow rate. The ones without control will produce water at the same rate as before, but at a lower temperature. Sometimes I have seen the input stopcock partially turned off like this on boilers that do not limit hot water flow rate so as to ensure the hot water temperature remains hot enough without the user having to remember not to turn the hot bath tap full on. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
"Christian McArdle" wrote in message
. net... If I can get my sealed system up to at least 1.5bar by filling it from the mains filling loop, does this mean I have enough pressure to fit a combi boiler? Yes it does. 1.5 bar is easily enough for a combi boiler. However, it doesn't tell you if the flow rate is good enough. Flow rate is more important than the pressure. You mention 9 lpm elsewhere, which is not enough flow rate. However, this poor flow rate might be for a fixable reason, such as a broken/partially closed stopcock, or a modern styled tap with very narrow waterways that is not designed to pass more than that flow rate. (I'm not suggesting that the tap would need replacing, just that it might affect the feasibility test). If you have a garden tap, try measuring the flow rate off that instead. Christian. ok, I've measured it at 15 litres/min outside at the garden tap. Better, but not outstanding.... Jim |
ok, I've measured it at 15 litres/min outside at the garden tap. Better,
but not outstanding.... I think that`s similar to ours, and recently had our first central heating system installed - a Worcester Bosch 28 SiII IIRC... Works just fine :-) -- Please add "[newsgroup]" in the subject of any personal replies via email --- My new email address has "ngspamtrap" & @btinternet.com in it ;-) --- |
In message , John
Rumm writes andrewpreece wrote: Check that if you have a stopcock or isolation valve/tap in the line that it is fully open. My initial flow rates were rather disappointing until I realised that the combi was fed from an isolation tap, which was only cracked open halfway. Some combis control the flow rate of hot water produced, Which ones and how ? I can't think of any. Every boiler I can think of which has dynamic control over the DHW temperature does this using a modureg - a gas valve which varies it's output depending on the temperature of the water coming out of the heat exchanger The information contained in this post may not be published in, or used by http://www.diyprojects.info -- geoff |
On Wed, 20 Oct 2004 20:32:56 +0100, "JJJ" wrote:
"Christian McArdle" wrote in message If you have a garden tap, try measuring the flow rate off that instead. Christian. ok, I've measured it at 15 litres/min outside at the garden tap. Better, but not outstanding.... Jim It suggests that by some improvement to internal plumbing, perhaps stop tap, etc. you could get a pretty good result. ..andy To email, substitute .nospam with .gl |
On Wed, 20 Oct 2004 21:47:59 +0100, Colin Wilson
wrote: ok, I've measured it at 15 litres/min outside at the garden tap. Better, but not outstanding.... I think that`s similar to ours, and recently had our first central heating system installed - a Worcester Bosch 28 SiII IIRC... Works just fine :-) I guess that it depends on what your requirements and expectations are. A loft tank arrangement with 22mm pipework etc. can comfortably deliver 15-20lpm per tap albeit at lowish pressure - with a pump rather more. If you are used to this, then 10-15lpm is going to seem poor. OTOH, if you are used to an electric shower, it may appear brilliant. ..andy To email, substitute .nospam with .gl |
raden wrote:
Some combis control the flow rate of hot water produced, Which ones and how ? How? no idea, never studied one close enough... I can't think of any. They certainly seem much less common these days, I don't remember finding any recent models that behave like this, the ones I have seen have all been typically ten years old or more. Every boiler I can think of which has dynamic control over the DHW temperature does this using a modureg - a gas valve which varies it's output depending on the temperature of the water coming out of the heat exchanger IIRC the Myson (monster sized thing, forget the model, but about 15 years old 120K BTU) that is mounted on the kitchen wall in my mum's house would seem to be one. The multipoint(s) she had before that (one was a Main "Severn Five") also regulated the water flow (to a feeble trickle in winter!). Also I thing my current next door neighbours has an (ageing) non modulating boiler that also seems to. I will have a closer look at the model next time I am near it. (IIRC our pet troll was insisting that his "Boiler of the Month" from a few months ago (the CB50 was it?) would "never run cool" - so based on that quality evidence perhaps you are right, there are no current models! ;-) ) -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
"John Rumm" wrote in message ... raden wrote: Some combis control the flow rate of hot water produced, Which ones and how ? How? no idea, never studied one close enough... I can't think of any. They certainly seem much less common these days, I don't remember finding any recent models that behave like this, the ones I have seen have all been typically ten years old or more. The Worcester Bosch Greentar combi 40kW, has flow regulator.IT can be set on commissioning. You set the flow to the required litres/min and it stays there. You can't turn the bath tap on full and just get warm water as the simpler models do. (the CB50 was it?) would "never run cool" - so based on that quality evidence perhaps you are right, there are no current models! ;-) ) What evidence would that be? The CB50 allows full belt then when the stored water drops below a set level the water regulator maintains approx 11/litres/min flow through the unit. The older HIghFlows don't run out of hot water, well on the older models you had to lower the flow at the tap to heat the water up when the store was exhausted. |
On Wed, 20 Oct 2004 20:32:56 +0100, JJJ wrote:
"Christian McArdle" wrote in message . net... If I can get my sealed system up to at least 1.5bar by filling it from the mains filling loop, does this mean I have enough pressure to fit a combi boiler? Yes it does. 1.5 bar is easily enough for a combi boiler. However, it doesn't tell you if the flow rate is good enough. Flow rate is more important than the pressure. You mention 9 lpm elsewhere, which is not enough flow rate. However, this poor flow rate might be for a fixable reason, such as a broken/partially closed stopcock, or a modern styled tap with very narrow waterways that is not designed to pass more than that flow rate. (I'm not suggesting that the tap would need replacing, just that it might affect the feasibility test). If you have a garden tap, try measuring the flow rate off that instead. Christian. ok, I've measured it at 15 litres/min outside at the garden tap. Better, but not outstanding.... Not brilliant but likely workable. -- Ed Sirett - Property maintainer and registered gas fitter. The FAQ for uk.diy is at www.diyfaq.org.uk Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html |
On Wed, 20 Oct 2004 22:49:02 +0100, Andy Hall wrote:
On Wed, 20 Oct 2004 20:32:56 +0100, "JJJ" wrote: "Christian McArdle" wrote in message If you have a garden tap, try measuring the flow rate off that instead. Christian. ok, I've measured it at 15 litres/min outside at the garden tap. Better, but not outstanding.... Jim It suggests that by some improvement to internal plumbing, perhaps stop tap, etc. you could get a pretty good result. I agree that arttention to detail can make the difference here. Using full bore 1/4 turn stop taps and getting the cold feed to the boiler before other usags can make a difference. -- Ed Sirett - Property maintainer and registered gas fitter. The FAQ for uk.diy is at www.diyfaq.org.uk Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html |
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