What did you do today (2015)

The building we worked in Milton Keynes had plastic pipes in the concrete base. These were supposed to cool the concrete and they had fan units in the floor blowing into the underfloor space and over concrete to cool the air.

Outside they had a cooling tower that had a fan up draft, this whole set up was costing approx £3700 per annum on top of power requirements. This being the twice annual maintenance and Biocide costs.

You may guess the out come as women sitting over or close to the floor outlets wanted to move as they started getting a frozen leg syndrome. In the end I recommended turning the whole system off and there were no more complaints and it cost less. From this I learnt that the soil was a standard 11C temperature and was very stable as we monitored the system 24/7 with recorders.

Clive

" Someone in the village has installed an air source heat pump."

Oh dear Bazyle - guilty as charged I'm afraid - we have just installed one ! It has a largish fan and I guess it does produce some noise close by. In mitigation we are not close to other properties in the village. These pumps are quite popular here and several of our neighbours have them. It is early days but (I hope!) it will be the solution to our heating problems. Up to now we have been dependant on oil fired central heating (and big price swings) plus a woodturner - there is no gas out here in the sticks. It is, it seems, a different philosophy of heating - it is not hot but an even, comfortable, temperature throughout the house at all times.

( My wife also insists on an open bedroom window at night - we will see how that pans out in the colder weather!)

Norman

Nobody has mentioned it, but if you are on the gas supply grid going for solar/air or ground sourced heat will cost too much. Pay back periods exceed the time the average occupier stays in that house and I for one would not be too impressed with a higher house price just because of "eco" heating.

Heat pumps have a "gain" factor (Coefficient of Performance or COP) of 3+, ie for 1Kw electrical input you pump 3+Kw of heat, but then electricty power costs 3x that of gas power, so where is the advantage? The factor would need to be at least x5 plus low unsubsidised install cost to be attractive.

Edited By KWIL on 07/11/2015 23:17:40

Norman,

Never open a window, I have the advantage of a Mechanical Whole House Heat Recovery System, air and hence heat (+ water vapour) is drawn from Kitchen, Bathroom etc and dumped to atmosphere via a cross flow heat exchanger which warms the incoming ai, which is piped to all the other rooms. End result, clean fresh warm air and no need to open the windows at night!!

K

That's what I was inferring earlier also that prices are artificially high because people are "saving money" or so they say which in many cases they wont be considering how long it takes to recoup the cost. It also gets less attractive as people age. There comes a point in life where people are unlikely to ever recoup the cost.

Condensing boilers don't work out too well when installed on older systems either as they generally don't have sufficient radiator area. To make best use of them systems need designing from scratch specifically to suit this style of boiler so that it can actually condense. There is a bit about that here

**LINK**

The problem is that prior to this style of boiler being used the design temperatures were too high and a lot more radiator area is needed to make good use of them.

John

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grrrr. Workshop dehumidifier made horrible noises (3 yrs old) so replaced with Dimplex from Screwfix. Just been to workshop and find new water sucking machine sitting in a puddle. Assume something wrong with drip tube so looking into that when I see the tank which I had taken out and set aside was now sitting in a puddle. The moulding ingate left a small hole right in the middle of the bottom. Few seconds with soldering iron has it sealed but I now have 2 damp patches in the chipboard floor. Hope it dries this out before they have a chance to swell.

I installed a condensing boiler some 3 years ago on a system which I designed and fitted 27 years ago. The exhaust plume indicates that it condenses most if not all of the time.

Flow temperature is controlled by reference to the outside temperature (ie weather controlled reference). All Rads are fitted with wax thermostats for room temperature control and the master thermostat is fitted in the inner hall where there are no radiators. When the time clock shuts the system down there is a fall back (night set back) temperature level set which over rides the clock if the core temperature falls due a sudden overnight drop in temperature.

Result, economic constant comfort levels, properly controlled. All floors, ceilings and walls are more than fully insulated with complete double glazing.

In Christchurch NZ, open fires are banned, and only approved closed log burners are allowed, but the form of household heating that is preferred is the heat pump, and after the 2010/11 earthquakes heat pumps were supplied to replace damaged fire places.

My heating is by a Night Store heater, a pile of bricks heated by electric elements, it is switched on and off 11PM, 7AM by the same ripple control that switches the hot water cylinder(this is at a cheaper rate than the normal heating and lighting)

The Christchurch Drainage Board uses bio gas at the sewerage works to make fuel for it's vehicles, and to generate electricity with two old, large diesel engines (ex marine, about 5000hp each).

Ian S C

Lots of cynicism about heat pumps and condensing boilers on here, surprise, surprise, much of it anecdotal, ill-informed or simply urban myth.

I got an air source heat pump fitted in our house in Canada when the original system started to show signs of corrosion after 30 years. The system is very similar to a standard aircon system, ie well proven system compts, the main difference being that a heat pump is bidirectional. It all sounds terribly mysterious but it's basically just a heat exchanger that can operate in either direction. Essentially during the summer, the outside heat exchanger of the heat pump is hotter than the outside world (and thus cools the house). In the winter, it is cooler than the outside world and consequently heats up the house. We retained a gas-fired furnace as a backup and for when the ambient was below 0C but in practice we hardly ever needed it (Vancouver weather is like the UK). Many people simply have an electric heater to boost the system in the winter but in our case the house wiring would have been a problem. Didn't actually cost a lot more than a std system to install and there were grants available to subsidise more efficient heating systems, rather like in the UK.

The reason heat pumps are lower cost is because of their thermodynamic coefficient of performance (COP) which is something like 4 or so for these systems. A COP of 4 would mean you only pay for 1kWh to create 4kWh of heat effect, unlike an electric heater which has a COP of 1. So even if you are using more expensive electricity to power the system, it uses less energy and still costs less than gas or electric heating - with the benefit of aircon in the summer months. In many cases you can do away with the gas / oil / electric heating altogether.

The system components are very well proven, as they have been is use for many years across the world within aircon, refrigeration and heat pump systems. Our system came with a 10 year parts and labo(u)r manufacturer-backed warranty which wasn't unusual. Externally (hidden behind some bushes), there was a heat exchanger with a fan inside it that was about big enough to hide inside if you removed the guts. It wasn't much noisier than many modern condensing boilers (which also have a fan).

Not so convinced about ground source systems, given the extra installation cost and effort. One of the main obstacles to heat pumps in the UK must be the low demand and lack of awareness. This must push up the cost and probably limits uptake to mainly the eco-warrier / tree hugger minority. Pity - as they have a lot going for them.

Murray

In the UK we have timers on our meters that do the switch over - has the major advantage that the switch times of each installation is different (by up to an hour or two) so you don't get them all switching together.

> Not so convinced about ground source systems

Agreed, ground source really only makes economic sense if you have a really big installation and is best done as a borehole or using a water body that doesn't freeze. The problems come when too much capacity is squeezed into a small space.

Air source heat pumps are ideal for most UK domestic situations.

Neil

I've just finished installing an air-to-air heat pump, this is our second. The first one worked well but the electronics gave up. the problems were very similar to what I was reading about lathe speed controls. Our pump heats one large room. It feels like a 3kw fan heater but draws about 3-4 amps, and then not for long. Ideal for autumn-spring weather but does struggle when outside drops to -10. Non-scientific calcs. show it is cheaper than buying in hardwood for log-burner and a lot easier on the old back.

Unfortunately the UK market is distorted by regulation and profiteering, labour costs etc so a £1000 heat pump in Canada becomes £3.5k in the UK. Mild climate reduces use and extends payback time. COP falls dramatically below 5C source heat (when the gas mix is tuned for UK temperatures) so bad just when you need it and when using 'economy 7' (original 8 hour cheap rate in the 'sixties was reduced to 7 hours in the 'seventies once they had got millions signed up). Ground source is never <0C so has advantages there.
If using domestic airconditioning (rare in UK) a bidirectional HVAC system makes more sense.

Anyway in workshop damp patch next to dehumidifier dried overnight but he smaller one 4ft away has only just cleared. So it's not just Chinese made lathes that have defects.

Heat Pumps ... Great idea, if only they weren't so noisy.

Does anyone remember the [Electrolux, I think] refrigerator that had no motor and was almost silent in operation? ... I don't suppose that design could be scaled-up.

MichaelG.

There is a similar night storage system available in the UK Ian. This house had it in when we moved in. Gas worked out a lot cheaper when it was installed. Not sure how it compares now and the storage heater have improved as well. Some of the ones here were just a water tank but the electric people provided a cheap top up sometime around mid day. It was probably installed in the 60's maybe 70's.

I put the gas heating in about 20 years ago and at that time most people were installing 80 - 60C systems as mentioned in the link I posted. Microbore was having problems due to the people installing them hence having to do 10mm myself but with a length limit due to the size of the radiators needed for 60C running. The 80C types would only really be need to be run at that when it was very cold but that's when the heating spends a lot of time on. The last paragraph in the link explains the problem. Insulate the house so that the 80C rad temperature isn't needed at all and things get different. Change radiator sizes and different again. On new builds now it's all well sorted out. Live in a 3 story 5 bed solid wall house like I do and things aren't so easy but fortunately the radiators are big enough to make good use of a condensing boiler. No hot water tanks and a vented system to make replacement difficult. Solid floors and some odd pipe runs so a sealed system might have problems without some rather large expansion vessels. We use a heat store for hot water so there is no run up time as there is with combi's. The boiler hardly ever comes on to keep the store up to temperature so I'm not keen to change that aspect. We don't have any heating on the top floor. The roof is insulated and the lower floors keep it warm.

We ran it with no thermostat for a long time, unusual at the time and just used the radiator valves. Pump life suffers though so eventually I fitted a thermostat. Never been happy were it was really - in the room with the boiler uncontrolled over run radiator so just bought one with a radio link from the thermostat to the controller so I can move it around. Currently in the living room along with 2 rads with wax stats. This is a don't do but the results so far look like they will be of some benefit to the gas bill. The over run radiator is in one of the bathrooms so guess that might get a little bit warmer than needed - so what.

John

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Edited By John W1 on 08/11/2015 12:12:11

Silent fridges are now in widespread use - ideal for hotel rooms and bedrooms. But they are based on Peltier cells (which are consequently available for peanuts on ebay / AliXpress etc). Didn't there also use to be gas powered fridges at one time?

The system in the mother in laws bungalow is oil fired as there is no gas, originally the little estate was designed with a central oil tank for all the homes but that fell by the wayside although the infrastructure was put in place. Fitted a new oil condensing boiler outside the bungalow next to the oil tank which is new and fire resistant so can be put just about anywhere. The boiler has an internal hot water store so hot water is almost instant all be it you still need to run off the cold water in the pipes. I tend to over size radiators such that that the water temperature on the flow can be lower for the same heat output which means the radiators are bigger, at present I have the flow temp set at 50 degrees C. It also gives a bit of flexibility as if it gets really cold out I can turn it up.

Bob

The run up time is going to be the same regardless of what you have at the boiler end. It's due to the column of water standing in the pipes between it and the tap. Not only do you have to flush the cool water out but you also have to bring the copper pipework up to temp before full temp is achieved. Our Worcester Bosch combi heat exchanger was kept at temperature at all times and the full 30kW output was available through the hot water outlet if required.

The only way to avoid run up time is to have a circulating hot water system. In these, the hot water runs around a circuit rather like CH. When you turn the tap on, hot water is almost instantly available. Of course the downside is that you are constantly incurring heat loss from the whole circuit which is why they tend to be found in very high end properties.

In my view, the main downside of the combi system was the tendency of the control loop to fight the thermostatic shower valves - and the radiator TRVs fighting with the room thermostat (eg at my mother's house). With a system fitted with TRVs, it makes little sense to have a room thermostat and as mentioned it can actually cause conflict (boiler overtemp protection).

Murray

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The Electrolux fridge was a standard [evaporative cycle] unit, but with no compressor; it just had a small heating capsule inside ... and yes, there was a gas powered equivalent.

Seemed like a very elegant system; but it presumably had some disadvantage, or we would all be using them.

... It should be possible to drive one of these with direct Solar Heating from a lens or a parabolic reflector.

MichaelG.

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Edit: Interesting link here

Edited By Michael Gilligan on 08/11/2015 13:38:48

Many moons ago we had a small worktop fridge which was powered by paraffin, was a cracker if adjusted right it would freeze stuff,don't know if they can still be got

Mick

My Camper van has a Ga/Electric fridge. Just right for chilling a bottle of wine to go with the ready meal at the end of a days driving.