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overrun

A cost overrun, also known as a cost increase or budget overrun, involves unexpected incurred costs. When these costs are in excess of budgeted amounts due to a value engineering underestimation of the actual cost during budgeting, they are known by these terms.
Cost overruns are common in infrastructure, building, and technology projects. For IT projects, a 2004 industry study by the Standish Group found an average cost overrun of 43 percent; 71 percent of projects came in over budget, exceeded time estimates, and had estimated too narrow a scope; and total waste was estimated at $55 billion per year in the US alone.Many major construction projects have incurred cost overruns; cost estimates used to decide whether important transportation infrastructure should be built can mislead grossly and systematically.Cost overrun is distinguished from cost escalation, which is an anticipated growth in a budgeted cost due to factors such as inflation.

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  1. I

    Main combi eco 30 pump overrun

    Hi, I have noticed recently that when the central heating, set at 60 on boiler, goes off the pump no longer overruns for the period of 3 minutes like it always has. Is this a problem? With the dhw it does the 1 minute overrun still. Thanks.
  2. D

    Using HW Circuit for Pump Overrun?

    Hi, I have a Y Plan system with Glowworm HX system boiler vented system. The system as originally fitted has one radiator without TRV (Landing) but also has a gate valved controlled by-pass. The pump is controlled by an output from the boiler. Many years ago I added an Honeywell ABV and this...
  3. milleniumaire

    Pump overrun is killing my heating!

    Happy New Year. Okay, maybe the subject is a little dramatic, but hopefully I've got your attention for a few minutes šŸ˜€ After a recent upgrade of my CH system, which included a LLH and a new circulation pump, my trusty old Vaillant ecoTEC 637 Plus system boiler seems to be spending a lot of...
  4. B

    Thermostatic pump overrun temperature?

    A simple question, but so far I've not found a definitive answer:- Some older boilers use a thermostatically controlled pump overrun switch built into the boiler thermostat. They are generally factory set and not adjustable. At what temperature should it switch? I'm specifically referring to...
  5. B

    Glowworm Fuelsaver MK2 Pump overrun

    I have an old Glowworm Fuelsaver MK2 in a Y plan installation. It's still working ok apart from an issue with the pump overrun... As of 2/3 weeks ago, when the room stat switches off the boiler, there is sometimes a thump in the vent/expansion pipe as hot water / steam is pushed up into the F&E...
  6. A

    Pump overrun causes loud bang

    Hello, I am not a plumber, but I have done some DIY in the past, so I have some experience. Following a new boiler install by a professional about a year ago, there remains an issue when the pump overrun initiates. The boiler is a Worcester Ri compact installed downstairs. the pump is...
  7. S

    britony overrun and heating

    hi all, first post but so much info on here, hope you can help. I have an old britony cobi 80 boiler which im having a couple of problems with, well one problem really. i turn on the hot water all works fine and as it should do.... i have the room thermostat set at 25 deg, both on manual and...
    • ste123
    • Thread
    • advise britony cutting first heating overrun pump running urgent weeks
    • Replies: 2
    • Forum: Central Heating Forum
  8. D

    Excessive Pump Overrun

    Hi, I've been searching for a while for an answer to this. Had heating engineer out today to look at the boiler. Problem is that the pump is coming on at 2AM, 4AM, all hours. The rads upstairs have their valves open only a little so the water's quite audible. Apparently, this is the overrun...
  9. fronty

    Could lack of pump overrun cause hex problems in the future?

    Just thinking... my new boiler (a Viessmann) was installed without pump overrun, apparently it's not required because it has a stainless steel heat exchanger, but when the burner cuts out I see the temperature slowly rise (as reported by the boiler) to around 95 degrees, I assume this is the...
  10. D

    Pump overrun bypass with variable pressure pump

    This topic has sort-of been touched on in a couple of other threads, notably 'Two questions about a bypass valve', but I haven't quite found the answer I'm looking for. I have a Potterton Suprima 80 boiler (non-condensing, old-school) and recently replaced the old constant-speed circulating...
  11. D

    Pump overrun issue thread closed

    I have just had my question, which was asked honestly and in good faith, closed unceremoniously by someone who accused me of "fishing" instead of calling an engineer. The accused should be allowed right of appeal, especially when injustice is so obvious. Not sure what "fishing" refers to but I...
  12. D

    Old boiler has pump overrun issue

    I have an old Apollo 60B which is running well but has an intermittent boiling issue. It seems to be connected to the pump overrun stat but it works correctly most of thetime and I would be grateful for advice. Intermittently ā€“ once every few days - water boils in theboiler for a few seconds...
  13. G

    Pump Overrun

    Hi ALL, Ideal Logic Heat + 15 heat only (not combi) boiler keep running (not burning) about 2 minutes after heat demand stops, seems like pump running 2 minute as well to get heat away from boiler inside. Just wondering Am I right, in this two minutes one of the zone valve must be open to get...
  14. T

    CH pump overrun

    Boiler is a WB Greenstar CDi conventional 40. Pump is connected to LzNz. The pump runs constantly ie provided the boiler has power, the pump runs. Any suggestions as to what needs to be done so that the pump cycles till the boiler cools and then switches off. Tom
  15. J

    Retro pump overrun

    Want to arrange pump overrun. Current system, pump and boiler controlled by timer, when boiler cuts out on control stat. pump continues to run, no problem. When boiler and pump stop together on timer, residual heat is not dissipated and high limit stat. is thrown requiring manual reset. It is...
  16. M

    Pump overrun issues HELP PLEASE

    Hi all. Was instructed to replace an ideal classic with a Worcester 18RI. Quoted (including electrics) and started the job. The customer was clear in saying he didn't want any modifications to the cylinder etc. The system is a thermal store with 2 pumps a room stat and cylinder stat. When the...
    • MDS PLUMBING
    • Thread
    • boiler cylinder help issues overrun please pump pump overrun system wiring
    • Replies: 9
    • Forum: Plumbing Jobs | The Job-board
  17. C

    Two pump multiple zone wiring diagram with pump overrun and mid position valve

    I had an original central heating/hot water system incorporating a single pump, single room stat and a mid-position valve. I have now built an extension and extended the heating system so that I have 2 pumps and an additional 3 zones each controlled with its own valve and stat. There is a single...
    • craigskelly
    • Thread
    • diagram forum mid position multiple overrun plumbing position pump pump overrun valve wiring zone
    • Replies: 5
    • Forum: Plumbing Zone
  18. M

    Replaced boiler feeding thermal store cylinder.

    Hi all. In need of some advice...... I have a customer who's boiler was classified unsafe. The existing system was a heat only boiler feeding a thermal store with no Y plan or S plan etc. My priory was to isolate the system, flush it and replace the boiler before Christmas. The issue I have...
    • MDS PLUMBING
    • Thread
    • boiler cylinder feeding oil overrun replaced store their thermal thermal store
    • Replies: 5
    • Forum: Plumbing Jobs | The Job-board
  19. B

    problem with pump and fan overrunning after swapping pump

    Hi i hope someone can shed some light on a problem with my Glowworm Xtramax boiler. I have moved to a new house and recently Ive disovered a weep or two from my HW pumps manifold housing which i can only assume is a hairline crack hard to tell or see (it looks like previous owner may have...
  20. W

    Ideal 35 + combi boiler pump overrun

    Boiler working fine, heating and hot water perfect, no faults on display, apart from pump overrun coming on when no heat called for. ?? If flow and return was back to front could this possibly cause this?
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