Pumping Hot Air

I went to see an air source heat pump installed in a loft today. I was invited to view the installation by the manufacturer because I expressed doubts about the viability of a heat pump in a loft.

I like to think I approach things with an open mind, but don't we all. Seeing the unit in action confirmed my worst suspicions but what I really wanted to witness was the noise level. It was actually quieter than I thought it would be but there was still a low hum vibration transmitted through the roof timbers across the top floor of the house and the huge fan moving air through the enclosed space of the loft was also clearly audible. The unit was less than a year old and it's in the nature of all appliances with a fan to get noisier. How many hotel air conditioning units have kept you awake at night? Or is it just me who stays in cheap hotels? The rep's reaction was to suggest that "You can turn it off at night". That is fine provided you don't need hot water first thing in the morning.

There is nothing wrong with the heat pump as such but putting it in a loft is self defeating. Apart from the noise the heat pump is cooling the loft. Again the rep, paid to defend it at all costs, told me that it was only lowering the loft temperature by 1 1/2°c. How they know this is anybodies guess because that figure must fluctuate wildly according to a number of factors such as outside temperatures and wind speed, but even if it were true it's not something to boast about. The whole point of a heat pump is to extract heat from the air so the more it grabs the better. The problem is that the colder you make the loft the greater the flow of heat from the house below. Basic physics dictates that hot will always flow to cold and the greater the temperature difference the faster the flow. "Ah yes but you can insulate it" said the rep. He is right of course and the idea would be that if the loft were cold and the house was well insulted the heat from outside the roof space would flow in to replace the heat pumped out but this loft was very badly insulated so the chances are that the temperature of the loft would be raised by heat escaping from the house. In some areas of the loft there was a 100mm of glass fibre which is inadequate and in other areas nothing at all, just the ceiling. On the plus side the heat pump captures some of the heat escaping from the house and returns it, but it takes energy to do that and it would be better to stop it escaping in the first place. Spending a fraction of that money spent on a heat pump to improve the loft insulation would have been far more cost effective and far greener.

Leaving aside the noise issue and the lack of insulation, the sole purpose of the heat pump in this particular house was to heat domestic water. Is this an economic prospect? Because the house has a gas boiler the answer has to be no. Solar panels would have been a much better bet because they use a minimal amount of electricity for the circulating pump.

The COP of the air source heat pump is around 2 at 50°c and the hot water needs to be 60°c to prevent legionellea so it still has to be topped up by the gas boiler or electricity. The heat pump is only running during the day (too noisy to run at night) so there is no off peak electricity to take advantage of, and a COP of 2 with peak rate electricity is no better than a gas boiler.

OK you could bring the cylinder up to 50°c during the day and top it up with off peak at night but with most tariffs you need to use a fair amount of off peak to compensate for higher day time rates. The whole thing is a minefield.

What concerns me most is that this sort of ill thought out installation (which don't forget the company put up as a show piece) will harm the cause of heat pumps. This is over-selling the technology. There are plenty of other places the heat pump could have been placed around the property which would have been better and there are plenty of jobs it can usefully do but it needs to be fed into a large reservoir of water in order to stop it switching on and off all the time. Nothing shortens the life of a heat pump more than switching it on and off all the time. Competing with a gas boiler to provide just the domestic hot water is the least viable application.

I didn't share my views with the householder because she is a very nice girl who is looking to do the right thing for the environment. It's just a pity that she wasn't given better guidance by the salesman.


Roger Bisby
Information for Building Projects, Renovation and DIY at SelfBuilder.net

Living in Fear

I got a call last night from the police. My mother had been burgled. The guy came into her living room while she was sitting watching television and stole her bag with all her money.

I went round to her house and made sure it was secure. Understandably she didn't want to stay there and is now terrified. I know I'm not alone in feeling very angry about the way that crime has taken over this country. If my kids go out for the evening there is always the concern that they might be attacked by some knife wielding drug crazed moron or even just a stone cold sober moron.

It is a very tired cliché to say that my mother's generation came through the war and are now living out their old age in fear from the enemy within, but it's true and nobody could ever imagine that this country would turn out to be so dangerous for the old and the young.

So now she will live under siege in her home and I will learn more than I ever wanted to about locks, chains and alarms. It reminded me that some years ago I took part in a security makeover show for the BBC in Manchester. We visited the most burgled street in Britain and spent a couple of days putting in all sorts of security products for the resident.

There was one elderly lady at the top of the road who was living behind locks and bars on every window and she was lamenting the fact that what was once a good street had turned into such a terrible place. We fitted a wireless burglar alarm for her and I went through the procedure of arming the ground floor zone so she could sleep safely upstairs with the ground floor protected against intruders.

She was around 85 at the time and though she was very well turned out and as sharp as a pin I took the explanation of the controls very slowly. She stopped me half way through the demonstration and said "You think I'm stupid don't you?". I denied it but she had clearly detected my patronising tone.

"Let me just tell you that during the war I worked on top secret scientific instruments. Just give me the instruction booklet and make us a brew. If I've a question I'll ask you."

I could have kissed her for her fighting spirit.


Roger Bisby
Information for Building Projects, Renovation and DIY at SelfBuilder.net

Bucking the Market

My daughter, Georgina, has just bought a house so it looks like I will be busy doing 'voluntary' work on it for a few months. The fact that she has bought a house at this time is either seen as canny or foolish. Some people think it is a bad time to buy because they see predictions of house prices falling still and some think it is a good time because they believe things are bottoming out.

Nobody knows which will turn out to be the case so it's a punt, or at best an educated guess. A year ago the price she paid for this property would have been seen as ridiculously low, now it's the market price. If prices fall by an average of 30% as some predict then conventional wisdom says she will have paid more than she need have. But the key word here is 'average'. Because the average market price falls, that doesn't mean all house prices will fall in line with the average. The likelihood is that the overpriced flats and new builds will take a hit but a house which has effectively bottomed out already will probably stay there. The price she paid takes account of market pessimism so if the prediction is for a 30% fall this is the reason it isn't selling at the moment but it doesn't necessarily mean it will go lower. There are people out there who believe that if they hang around long enough some desperate person will sell them a house for next to nothing.

There is a great deal of pent up demand in the housing market and we have stopped building at the very time that there is a shortage. Personally I have no desire to see house prices go back up, so a trickle of activity that doesn't open the flood gates is the best thing. The problem is that markets rarely work in that way. We have Bulls and Bears. At the moment it is the Bears who are dictating things but when the Bulls sniff a little blood it will be like Pamplona. People will get trampled in the rush and there will be those following behind who see it all disappear in a cloud of dust but have no chance of catching it.

This of course is just another prediction to go with all the rest out there and it means nothing because nobody really knows but, though following the herd is safe, it will never win any prizes.


Roger Bisby
Information for Building Projects, Renovation and DIY at SelfBuilder.net

Waste of Space

I attended a press event the other day for a manufacturer of water heaters and boilers. It doesn't matter which one because what I have to say broadly applies to them all.

The Chief Executive was proudly telling us how the company is driven by innovation and they showed us some of their latest ‘innovative products’. Though I didn't want to rain on their parade I was a little underwhelmed. Most of what they showed us were 'me too products'. A new unvented cylinder with an extra bit of insulation . An under-sink hot water heater that did nothing more than deliver hot water. Don't they all do that. They showed us pictures of the heater installed under the sink. Who wants a water heater under their sink anyway? Once you have one of those in your cupboard there is very little space left for all the things that should go under there.
"Where else are you going to put it?" they asked me.
The company employs no less than 18 full time R&D staff and between them they hadn't managed to find an alternative place.

Space, or lack of it is the big issue these days. As land prices go up houses are getting smaller. Yet everybody wants more bathrooms and bigger kitchens but customers hate seeing anything to do with plumbing. Instead of designing new look casings and salivating over the sleek lines manufacturers need to think up ways of making their products disappear.


How about putting that water heater in the kick space under the unit? A small removable cover in the bottom of the kitchen cupboard to change the immersion heater is all you need to see. The kick space under the unit is dead space in all kitchens. Why not put a central heating boiler in there while you are at it? Why do boilers all have to be the same size and shape?. It makes no sense to have a boiler taking up kitchen cupboard space yet making them fit into cupboards has been the holy grail of boiler design for years. Yet when you take the casing off a boiler the components are anything but the shape that covers them. A cylindrical boiler with a coil heat exchanger shouldn't be hard to design. It could even lie along the top of some wall units, tucked in at the back.

A new solar cylinder was also unveiled at the do, but it looked like every other cylinder except that the extra coil makes it almost as tall as a man. What modern home has space for a 210ltr solar cylinder?
Why not make it so it can lie on its side in an eaves cupboard or why not make a matrix of hot water tubes that can be placed inside the 100mm space of a stud wall. The space between floor joists is also wasted. Why not make a boiler to go in there? There is around 350mm of gap between joists and it is often 200mm deep. Again a simple trap door would do for servicing.

Haven't they noticed that there is also a lot of space under the bath? What a perfect place for a water heater or a boiler. At present in design terms there is very little to choose between one manufacturer's products and another. What we need now is not lip service to innovation but some real ideas which address the needs of installers and end users. Manufacturers need to think outside the box to give the market some real choice and the market will then respond with some enthusiasm.


Roger Bisby
www.selfbuilder.net

Changing the Script

When I was trying to get cavity wall insulation in my house I started by phoning a cavity wall insulation firm. Well it seemed like a good place to start. The man told me that they could do my house for £450.00 but if I went through my energy supplier I would get it a lot cheaper because of a government grant.
I phoned my electricity company and the guy asked me for the age of the property.
"1905" I told him.
"Ah sorry that's too old."
"What do you mean too old?"
"It won't have cavity walls. They didn't start putting cavity walls in until around 1936"
"How do you know that?" I asked.
"Because it is written on my sheet"
"Well I can assure you that my house has got cavity walls"
"That will be very unusual"
"No it won't there are thousands of them in my area all built before the 1st World War and all with cavities.
"No they won't be proper cavity walls"
"What sort will they be?"
"I don't know but we need 50mm cavities ".
"Mine are two inches which is 50mm"

After a little more persuading he took my details and told me a surveyor would be in touch. Nobody called and after a couple of months I called back. There was no record of my call so I started again. It was all going so well until we reached the question about the age of the property.
"Oh no sorry that is too old"
"You are going to tell me that cavity walls were invented in 1936 by a man named McCavity."
"I don't know who invented them but 1936 is the oldest property we do."
"Look I don't want to appear pushy but I have cavity walls and I want them insulated so can't you just forget the date and fill in the form."
"It's no good the computer will reject it."
"So tell the computer 1936."
"I can't. These calls are recorded."
"Yes I know, for training purposes."
"Yes."
"So why don't they tell the people they are training with these calls that cavity walls go back to just after the turn of the century? "
"I don't know the answer, I can't help you any further. I'm sorry. If there is nothing else......"
I left it for a few months and called them back
"Age of property?"
"1936"
"OK, how many bedrooms does it have."
"Is there a right and wrong answer here because now I've got to level two in this game I don't want to blow it?"
"We just price the job on the number of bedrooms the surveyor will check".
That turned out not to be the case. In fact the surveyor didn't even turn up and I was beginning not to care.
I was worn down by the whole process. I left it a few months and in a fit of enthusiasm and annoyance I called up. The man explained that they were busy and I would just have to be patient. I thought I had been but he means more patient but I was grateful that my name was still on the list. Eventually a surveyor turned up.
"This house looks old when was it built?"
"1905"
"That's too old. It says here 1936"
"A mistake probably but don't worry it has cavity walls and they are the right size, it is a perfect house. It is crying out for insulation. My neighbour has cavity insulation in his 50mm cavity and they were built in the same year".
"OK I'll put it through but don't blame me if they can't do it."
The guys that eventually came and did the job were unphased by the age of the property. In fact they told me that they preferred older houses because the mortar is sand and lime so it is easier to drill.
"We wish they were all like this"
"Well I can tell you why you don't get more of them". I said.
In truth after all the fuss and delays it was worth the wait. The house is a lot warmer, especially on windy nights when the wind used to whistle around the cavities and found its way in through the small gaps around the joist ends and up through the floor boards in the bedrooms. Stopping that air movement is really a large part of the saving. Cavity walls were after all initially designed to trap air in between two skins of brickwork so, in theory, they should form an insulating layer but they could never make them airtight without mastics and neoprene seals. The air could still run in and out through shrinkage gaps around windows and tiny gaps in the mortar around pipes etc. Filling them with insulation simply stops the air moving around so much and creates micro pockets of trapped air.

All insulation works in this way and it only works when it is dry. The thing that concerns many people about filling cavities is that damp can travel across the insulation and this needs to be considered especially on walls exposed to driving rain. It hasn't happened on my house and it hasn't happened on my neighbours. The guys that pump in the insulation tell me it is very rare to get problems. They shared my view that the house was well built and the age isn't an issue but I had to lie to get it done.

I wonder how many pensioners, in dire need of cavity insulation to help them reduce their winter fuel bills, have been rejected by their energy suppliers because their property is 'too old'. Unless they happen to have some knowledge of building construction they would probably take the word of the kid in the call centre and resign themselves to the fact that it is another one of life's little treats that they don't quite qualify for. And the kid in the call centre is just working from a script but I get the feeling that somebody needs to change that script.


Roger Bisby
www.selfbuilder.net