Regional Winners

Please tell us about a project you are particularly proud of – what was the problem and how did you solve it for the customer?

This was a fantastic opportunity for ourselves as it was our first ASHP installation and not only that but the installation is in the Georgian gatehouse to Doxford Hall built by a locally famous Architect John Dobson and set on the beautiful coastline of Northumberland. The property itself is the Pavillion gatehouse to the main hall, Doxford Hall which is ran as a hotel.

Originally the job was specified by the land agent and had been specified to have no heat pump and using an overlay underfloor heating system throughout the property but upon winning this job we completed a room-by-room heat loss and quickly found that the original specification was inadequate and would not work as the heat loss exceeded the capabilities of such a system. The main issue to overcome was getting the client to realise that unfortunately the original design was not viable and would need to be readdressed.

We eventually agreed with the client and main contractor to a screeded system which in turn led to the pretty drastic decision by the client to remove all the timber joisted floors throughout and backfill then subfloor and screed a new floor throughout the property to achieve a higher output from the underfloor heating system. This combined with further insulation measures all round brought the heat loss back down to an acceptable level and allowed us to design a system that would work well.

The client’s brief was to have an efficient and easily controlled system. They wanted us to design a system that involved using a heat pump but also had a backup system for the client’s peace of mind. Technically this was quite difficult as we were trying to design an efficient system around the heat pump but also to include the clients desire to retain the oil boiler as a backup. The property is used as a holiday home for the owners and as such they do not live there full time. However, they do visit regularly and have large family gatherings so another aspect of the brief was to also meet a huge hot water demand to cater for back-to-back bathing after family trips to the beach.

The client also wished to retain an existing library room. The floor in this room is an original parquet floor that was to be retained and restored and in this area the client wanted to retain a radiator circuit on a separate zone.

The main difficulties of this project were in understanding the clients’ needs and balancing this with the need for an efficient and well-designed system. In the end we settled on a higher flow temperature than we would have ideally liked but in doing this it allowed us to use a blended circuit for the radiators in the library which were replaced with triple panel k3s and sized accordingly to the room.

The controls also proved quite challenging as we had to provide third-party controls integration to the heat pumps in terms of the underfloor heating and third-party oil boiler controls and then also proprietary manufacture controls for the heat pumps which provide a radiator circuit, towel rail circuit, hot water and underfloor heating via two large manifolds. We have spent a lot of time setting up flow rates and concentrating on pump settings along with the manufacturing settings to ensure minimum cycling of the heat pumps.

As the home is used primarily as a holiday home, we had to provide the client with internet smart controls which by using the manufacturer controls to the zones we have managed to achieve.

Which products did you select for the job and why?

We specified two Vaillant Arotherm plus 12kw monobloc heat pumps which have been situated in a position externally in the garden and have been linked back into the property using a trench cut into the floor with the connection via Uponor duo pipe pre insulated conduit pipe work. Supply was still an issue when we started this project and Vaillant heat pumps were on backorder but luckily enough we found the two units on the shelf at a local MKM plumbing department that just happened to specialise in renewables and a new relationship for forged with the manager who was helpful throughout.

The heat pumps are paired with a 500L Vaillant Unistore hot water cylinder and a 210 Litre buffer tank. Specifying the correct 3 port valve also proved a challenge as Vaillant do not supply one with their kit on heat pumps this large in a cascade so we had to turn to sourcing our own valve that would not reduce the bore and offer full flow through the ports whilst still working with the manufacture’s controls. In the end we chose to use a Belimo valve as we could integrate this and it offers a full flow without restriction.

Vaillant sensocomfort controls have been used, providing a master control as well as a timer on the towel rail circuit and a thermostat on the library room. The system has been designed around the Vaillant controls and configured to only use the third-party oil boiler in the event that the heat pumps cannot meet the demand of the heating and hot water. Weather compensation is provided via a Vaillant external temperature sensor.

Underfloor heating we turned to a clipped system compiled by Omnie using two manifolds and the integrated Grundfos pumps and reliance blending valves as standard. UFH controls are used for individual temperatures of each room via Heatmiser Neo v3 wall thermostats.

Hot water is via the 500L Unistore cylinder and is complimented by a secondary hot water return which again was a conversation we had to have with the client as he wanted to reduce efficiency as much as he could. However, due to the long pipe runs in this large property and the client expectations it was deemed to be a necessary addition despite the slight impact on efficiency.

Tell us what was different or unique about this job? Why does it stand out?

This project was a special project to us as it was our first heat pump installation and therefore drew upon all of our previous knowledge whilst also learning alongside our training. We sought support from our contacts at Vaillant and had support from the head of renewables and a trainer from their training academy. Vaillant themselves did not have any schematics for such a complicated system and we were having to work between various different types of system schematics and take section from one drawing and integrate it to the schematic shown on another drawing etc.

Alongside this project we also studied for our company MCS via NICEIC which I am happy to say we completed and we were assessed on this project whilst also earning membership to RECC and Trustmark and to top that off an Oftec qualification.

The pipe runs throughout we feel are perfect and we have some great photos of really neat runs across the loft and distribution of hot water and different zones.

And finally, tell us what the end result was for your customer?

The end result we feel from our side was really successful and actually an enjoyable learning curve which I am happy to say has resulted in a really adaptable and controlled heating system for the customer which has met their demands on every level, given the complicated nature and top-level expectations, I think is a great success story.

The customer is really happy with the silent running Arotherm heat pumps which initially had been a concern but both the operation and the noise levels have proved to be very impressive. The third-party oil boiler was specified by the client as essentially a backup and again I’m really pleased to say that the oil level within the tank has not moved meaning the demand has been met by the heat pumps alone. Electricity wise its early days but the customer has reported the usage is well within the expectations and a good COP has been realised by the client along with an excellent SCOP so together we deem this a success.