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pressure loss
A loss-of-pressure-control accident (LOPA) is a mode of failure for a nuclear reactor that involves the pressure of the confined coolant falling below specification. Most commercial types of nuclear reactor use a pressure vessel to maintain pressure in the reactor plant. This is necessary in a pressurized water reactor to prevent boiling in the core, which could lead to a nuclear meltdown. This is also necessary in other types of reactor plants to prevent moderators from having uncontrolled properties.
Pressure is controlled in a pressurized water reactor to ensure that the core itself does not reach its boiling point in which the water will turn into steam and rapidly decrease the heat being transferred from the fuel to the moderator. By a combination of heaters and spray valves, pressure is controlled in the pressurizer vessel which is connected to the reactor plant. Because the pressurizer vessel and the reactor plant are connected, the pressure of the steam space pressurizes the entire reactor plant to ensure the pressure is above that which would allow boiling in the reactor core. The pressurizer vessel itself may be maintained much hotter than the rest of the reactor plant to ensure pressure control, because in the liquid throughout the reactor plant, pressure applied at any point has an effect on the entire system, whereas the heat transfer is limited by ambient and other losses.
I have an 8 year old Potterton HE Gold combi boiler losing pressure.
I have isolated the central heating to leave just water heating and it is fine. As soon as the central heating is introduced the pressure drops to zero within an hour. I have had floor boards etc up but cannot find a leak...
Hello all, hoping someone could help me with this, Boiler pressure is 1.5 bar, but when we turn on UFH pressure drops to 1 bar. then when we turn off UFH, pressure on boiler goes back up to 1.5 bar?? any help much appreciated
Dear All,
I hope you might be able to point me in the right direction with an issue I have with a 3 year old Greenstar 30i boiler, last serviced in Oct ‘22, with new pipe work all around the house at time of boiler install. We have separate circuits upstairs and down and a water cylinder.
At...
Can it be anything other than a leak?
The reason I ask is that I have had 4 plumbers/heating engineers out over the past 3 months and none are able to figure this out. System boiler powering a mixture of radiators and UFH. No detectable leaks by the rads, by the manifolds or really anywhere in...
Hello guys!
I had an Ideal Combi Logic+ C24 fitted in August 2021 in my mid terraced house and I started noticing that it was losing pressure during winter 2021.
I had the first engineer sent by Ideal in March 2022 when the pressure was going down very fast, I could see the gauge going down...
Hi folks - new here and looking for a bit of advice.
I've got a British Gas 532/i boiler which is struggling for pressure - around 0.5 bar.
Heating works fine through most of the house just struggles to get to the very top rooms.
I don't think any bleeding is necessary, and I cannot find a...
Hi all,
Recently moved into a new house and noticed the Greenstar boiler has low pressure on the dial.
Quick Google suggests using a key, valves, or fill loop to increase the pressure. Only problem being is I don't have either of those things.
Any help would be appreciated.
Cheers.
Hello. I need some urgent advice re water pressure in an unvented system.
A few months back, I had my gravity fed system + boiler changed to an unvented cylinder + system boiler. The water pressure following the swap was incredible. We were originally talking about putting in a mains booster...
My Ideal boiler pressure gauge pointer shows about 0.85 when cold (about 1.8 when the heating is on).
10 weeks ago the readings were 1.0 when cold and 2.0 when hot.
Clearly there is a loss in pressure over time. I can see no leak on any radiator or near the boiler. Is this pressure drop of...
Have a large CH system, not sure the volume but a mix of column radiators and UFH means it's probably 250L or more. Runs on a Vaillant Ecotec 630 that's been OK for 7 years, but recently started losing pressure (needs topping up weekly).
Had a new EV (old one was full of water apparently)...
I am a retired gas engineer. Corgi and Domestic Electrics + Building Surveyor. I have a Greenstar CDI 35kw that I fitted in my own home 15 years ago, serviced regularly, no issues till now. Suddenly its losing full pressure in approx 2 hours. I have concrete floors with buried copper pipe but...
My daughter has just moved into her first rental house with gas stove and hot water in Melbourne. The meter (pictured) definitely has gas connected to the regulator. But gas is not getting to the stove or water heater. The previous tenant had turned the gas tap off at the meter but it's on now...
Hi, hope someone can help me with a heating pressure loss problem. My valiant boiler has been loosing pressure over the last few months, resulting in me having to top up the water every week or so. Managed to get a boiler engineer to visit who diagnosed a faulty expansion tank. (Water evident at...
Hi
Towel rad in bathroom needs bleeding every few days and now noticed a small rad downstaris also has air in it regularly. Pressure drops every few days and needs topping up. I've tested with a flame for corrosion and it's clear, tried leak sealer and checked for weaping rad connections . I...
Have just moved home and had a Worcester Bosch Greenstar Life Gr8300iw 30 C installed. It has a thermostat which I had turned down low overnight (but not that low, 18 degrees C) and found the pressure had dropped to something like 0.3 bar the next morning. I topped it up but since then the same...
Hi all, anyone give any advice regarding our Bosch Worcester Junior 28I .... I have to keep re pressuring it every two weeks ( drops to 0.6- I put it back upto 1.2 and then it drops after 2 weeks).
Expansion vessel was re-pressured earlier this year by the installer . It is in warranty until the...
Hi all first post in this forum and hopefully someone can advise.
I have a warmflow external oil Combi boiler approx 4 years old.
Problem I'm having is this time of year when we start using the heating I am intermittently loosing all pressure on boiler and needing to refill, it has worked fine...
Hi all
I have a Halstead combi boiler in the loft about 12 years old, every week I have to raise my pressure back up as it nears zero, this has been ongoing for around six months.
I have recently started putting my heating on, when I turns it on I get an error code 3 for a few seconds, then...
Hi everyone. I recently had to replace my shower pump and increase the size of the cold water storage. Since moving to a gravity fed pump the pump is activating with no demand for a few seconds. The pump is now connected to all outlets in the house but I am concerned it will burn out if it...
If Isolating a boiler to determine if the leak is on the pipework or the boiler. If pressurising to 1.5bar then isolating the flow and return for an overnight test. Is it still acceptable to use the combi boiler for hot water? Expansion vessel located in the boiler.
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