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Everything posted by JohnMo
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Short cycling occurs when the heat source cannot get the heat away quick enough, or there is little or no demand, or flow rate is too low, or all three conditions. As the heat source goes through a start cycle the target temperature is exceeded by enough margin to cause the heat source to shut down, this repeats. To eliminate it, you can raise the target flow temp, add a couple degrees to the existing target temp. Then fine tune down. Or increase the system volume or flow rate. If you have the parameter available you can increase/decrease the PI integral time. This changes the reaction time of the controller. The way your system is setup can actually cause short cycling. If I run heat pump, so the circulation pump runs periodically, the temperature of the water close to the heat pump cools quicker than that inside the house, so heat pump thinks it needs to start up, but in reality it doesn't, heat pump starts, the warm water from house hits the heat pump it shutdown. This is fixed by running the heat pumping it's default mode of circulation when there is a demand for heat. The heat pump control then knows exactly when to restart - no short cycling.
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Not exactly true if you run an open single zone system as no heat.is wasted. But you do need the pipes that go to the cylinder insulated. With an ASHP that normally needs a buffer to get acceptable flow and cycle times, but also leads to less than ideal CoP due to flow temperature distortion, unless the buffer is huge and the flow through primary and secondary is perfectly matched, which it will not be.
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National Grid wants to move Electric meters to your boundary/garden
JohnMo replied to Temp's topic in Electrics - Other
What a load of ****. So a typical heat pump draws 8kW from the grid? The typical house in the UK only needs 6kW of heat so running a CoP of 3 that's 2kW - but more likely 1 to 2kW. This country loves to waste money. -
Carbon steel structures normally have a 3mm corrosion allowance. How quick the steel corrodes really depends on how you do corrosion prevention. And how damaging the environment is to the corrosion prevention and then the parent material. Is 2mm suitable? 100mm dia, I would be looking more like 6mm and then hot dip galvanised and not bother with the faff of concrete or gravel.
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Two bits of news on the US electricity market
JohnMo replied to Alan Ambrose's topic in Housing Politics
So give it another 10 years they maybe paying European prices, my heart bleeds for them. They don't have to consume so much electricity - forgot they need a huge walk-in fridge for all the food they buy at Costco and Walmart, because it's so expensive. -
Get prices from them and others, pretty sure their service doesn't come free.
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Two bits of news on the US electricity market
JohnMo replied to Alan Ambrose's topic in Housing Politics
But a normal car isn't, it's a V8 truck. Everything is cheap, so why would the normal person care. Electric is between 15 and 17 cents per kWh, so well under half what we pay? -
24v lighting circuit - good or bad idea?
JohnMo replied to SBMS's topic in Networks, AV, Security & Automation
That's what side lights are for, ours just switch on from a normal light switch - nothing like saying hold on a sec, while I get my phone out, need to reprogram the lights, it's a bit bright - moment lost - you will stay single for ever. No down lights in living room you don't need them, we have 8 up/down wall lights than never get used, and a couple of side lights that are used daily and that's in a room with 6m high high vaulted ceiling and about 38m². The only down lights we installed are about 120 to 150mm dia (depending on room), kitchen/diner has a whopping six of them. Nice even light across the whole room no shadows. 50mm downlights cast a narrow beam of light, so worth considering and the main reasons we did the polar opposite. -
Does your inverter with the battery, not supply the house in a power cut? We went AC coupled for that reason, grid off makes no difference, house runs as normal, PV string inverters don't see and difference so keep producing. We also have a geny with change over switch should battery run flat - need to get more petrol.
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24v lighting circuit - good or bad idea?
JohnMo replied to SBMS's topic in Networks, AV, Security & Automation
So how efficient is it running several miles of cable to the 80+ fitting? The 80+ light fittings isn't efficient either! That may look on paper, but isn't suitable for a property that has to last several life times - not mechanically strong enough. 80+ fitting your house must be huge to need that many, that's more than twice what we have (200m²)! Or are you going for an 80s show house vibe, with way too many down lights? Think you may need your head testing, too long thinking without real feedback - the problem of living alone. We had a house many years ago with dimmable lights, twiddled with once or twice, than thought what a load of sh!te. Never bothered again, nor will I in the future, nothing much to go wrong with a couple of light switches - one does side lights the other main lights - flick on once and off once per day. Our whole house wiring cost less than you will end up spending on just lights, so you twiddle a few settings then get bored. -
Will double glazed stable door be a problem?
JohnMo replied to Selfbuildsarah's topic in Doors & Door Frames
Maybe weight? Our doors are also double glazed, I chose to go double with Krypton gas fill instead of Argon. Brought the whole door U value down to 1.0. Really good door otherwise was 1.2 with Argon. think triple glazed was something like 0.8 for a door. (from memory, exact figures may be a little different - but not much). You could go vacuum double glazed for better than triple, but cost starts to get a bit silly. -
Identify the Swedish screw (and where can I source it?)
JohnMo replied to oranjeboom's topic in General Joinery
Not always, really depends what industry you are discussing, as many industries or even manufacturers describe bolts and screws to be different things although talking about exactly the same thing. The meaning changes between countries. When I went through my aviation training I was given very specific training on what a bolt and screw were and then in the oil and gas industry the terms were mixed and not very specific. A write up here https://www.accu.co.uk/p/131-difference-between-screws-and-bolts -
Identify the Swedish screw (and where can I source it?)
JohnMo replied to oranjeboom's topic in General Joinery
Yes, it isn't fully threaded it has a plain shank section, so technically a bolt. -
What to expect from an MCS follow-up visit?
JohnMo replied to sharpener's topic in Air Source Heat Pumps (ASHP)
Really depends doesn't it, if you paying a huge premium to the get the £7500, it's not really 7,500 All in I was less than £3k, fully installed, without taking any tax payers money. Win for me and the tax payer. Plus no one poking about my house that acts like this -
Amazing what you can find down a visual image search 300125_01_17.pdf fifm_rev.3.0.pdf
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Very large farmers sheds and buildings go up all the time, bet none of it has any local authority permissions, does anyone care - no
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What insurance needed to move in before completion?
JohnMo replied to YorkieSelfBuild's topic in Self Build Insurance
We never bothered with build insurance, but when we moved in work was still ongoing. Set up building and contents insurance in the normal way and ticked the box for work happening currently on site and then listed the minor and bigger jobs to finish. Didn't mention completion certificate as it wasn't asked - only answered the questions that came up truthfully. We are over 50% for timber cladding, no-one asked about it! -
What to expect from an MCS follow-up visit?
JohnMo replied to sharpener's topic in Air Source Heat Pumps (ASHP)
Another good reason to avoid MCS.
