Solar, storage and ASHP a winning combination in South Woodford

Overview

When the gas boiler in David Brewster’s modernised 1930’s North East London semi-detached house proved unreliable, he decided to replace it with an air source heat pump (ASHP). Working in harmony with solar PV and an energy storage system, his Vitocal 150-A heat pump now provides constant comfort and long-term peace of mind.

Time for a change

Although David’s gas-powered boiler was less than five years old, it often malfunctioned. As it was located in the loft, going up and down a ladder to fiddle with the controls each time was becoming increasingly inconvenient and problematic for the 75-year-old.

“I knew I had to do something about it,” he recalls. “And, in the meantime, I was reading up about heat pumps and thinking that acquiring one was something I could do personally about the climate crisis. Because change comes from all of us acting as individuals.”

Mixed opinions

However, not everything David was reading on the topic was positive. “There’s so much conflicting information out there, it’s a minefield,” he continues. “Some people say heat pumps never work, it’s all just a sales pitch. But when I dug deeper, I realised that couldn’t be the case. My grandchildren live in Estonia, where most people have heat pumps, and no one has gas. And in Germany, Sweden and Norway, they’re very widely used, too, so it made me think it must be nonsense, what I was reading about how bad they are.”

Further online research eventually led David to YouTube videos from Heat Geek, the low carbon training and technology specialist. “The fact that they train heating professionals to fit heat pumps properly was very reassuring. And they guarantee all installations completed by any member of their network. This gave me the confidence to take the plunge.”

Expert advice

The next step was to carry out heat loss calculations.

David spoke to several companies and was considering his options when Andrew Gilbert from Coolpower Electrical returned to the property to fit additional PV panels and larger battery storage. This followed an initial highly successful solar installation 18 months earlier which, according to David, worked perfectly from day one. “I took the opportunity to pick Andrew’s brains, as I knew I could trust his opinion,” David recalls.

Andrew strongly recommended contacting Alex Winters from Hertfordshire-based ASHP specialists Libtek Heating & Renewables. “Coming from him, that was a very high recommendation,” says David. “So, I thought I might as well speak with Alex and see what he said.”

When they met, Alex’s knowledge and professionalism made a very favourable impression on David. “I could see he knew what he was talking about. His calculations estimated the property had a heat loss of 9.2 kW, meaning we needed a unit that could output 9.2 kW at the design outdoor temperature of -1.7oC. This outdoor temperature is on the 99th percentile, meaning it gets colder than this only 1% of the time. He costed up three different heat pump options for me, but after reading all the information, I still wasn’t sure which to go for.

“I knew I wanted something decent that wouldn’t start to go wrong when the guarantee ran out. Because in the UK we haven’t yet got that track record of what heat pumps are like, I wanted technology that’s really been proven to work. So, I asked Alex, ‘If you were me, which one would you choose?’ And he said definitely the Viessmann.”

Quality and performance

Alex takes up the story: “We tend to advise customers to go with Viessman ASHPs because they have a built-in defrost buffer, so you never have to pull heat from inside the home during defrost cycles. That means better comfort levels, and you have that back-up too. They’re also manufactured in Germany to a very high standard and are known for their reliability, which was a key concern for David. Plus, the controls are good. You get a lot of parameters to set the system up how the customer wants it.” The fact that the Vitocal 150-A uses the refrigerant R290 (propane), which has a very low total equivalent warming impact (TEWI), was another significant advantage, as sustainability is also very important to David.

As David’s background is in the motor trade, he found it helpful to use car brands as a scale by which to assess the presented heat pump options. “When it comes to quality and price, we all know where we are if we talk about a Ford or a Vauxhall versus a Merdedes or an Audi,” he explains. “I asked Alex where he would put Viessmann, and he said definitely BMW, Mercedes or Audi. That told me what I wanted to know.” A reference visit to one of Libtek’s previous Viessmann installations in Enfield sealed the deal.

Timing

It was several months before the installation could take place, however, due to high demand for Alex’s services. Says David, “We first spoke in February, but the earliest he could find a slot in his diary was May. That suited us quite well though, as we wanted to wait for warmer weather before taking our heating offline for a week.”

In the event, the fitting took four engineers (two of whom were apprentices) five days to complete. This included changing four undersized radiators and adding two more, as well as fitting a weather compensation sensor on a north-facing wall.

Says Alex, “Lots of companies take five to ten days to do an ASHP retrofit install, but we prefer to put more people on the job and get it done quickly.

Results

In the three months since the installation, David has barely had to use any central heating due to the summer season. “What I can tell you though, is on cold days the heat in the house always seems stable – it never changes,” he remarks. “When we had the gas boiler, we used to turn radiators off in rooms we weren’t using. Now the whole house is warm all the time.”

As he’s also using excess solar energy to heat his water cylinder, his heat pump has only used 100 kWh so far, costing under £30. Alex explains further: “The water in the cylinder is heated by solar power to a base level of 40-45oC. This means when the heat pump turns on for Domestic Hot Water (DHW), it’s shooting straight up to 50oC, which satisfies the cylinder set point quickly but at a low Coefficient of Performance (COP) through summer of just 2.9. In fact, everything’s working really well. This is a perfect example of why you shouldn’t get hung up on COP. A low COP doesn’t necessarily mean a poorly performing heat pump.”

David’s new heating set-up is on target to bring him annual energy savings of £235-£961. And his CO2 emissions will be around 4.8 tonnes lower, according to projections made in the heat loss report and system design conducted by Winters. Meanwhile, he’s extremely happy with his new system. “I must say that Alex could not have recommended a better heat pump.”

Specifications

· 13 kW Viessmann Vitocal 150-A (9.5 kW @-1.7c DOT)

· 250-litre Heat Geek water cylinder

· 6 new radiators

· ViCare app

· Weather compensation

About Viessmann Climate Solutions

Founded in 1917 as a heating technology manufacturer, today Viessmann Climate Solutions is a leading global provider of sustainable climate (heating, cooling, water and air quality) and renewable energy solutions. The Integrated Viessmann Climate Solutions portfolio seamlessly connects products and systems via digital platforms and services, creating an individualized feel-good climate for users. Viessmann Climate Solutions is part of Carrier Global Corporation, global leader in intelligent climate and energy solutions. For more information, visit www.viessmann-climatesolutions.com

Press Enquiries Claire Dumbreck, Propel Technology, +44 7768 773857, claire@propel-technology.com