Why it's important to get underfloor heating installed correctly!

Why it's important to get underfloor heating installed correctly!

Underfloor heating isn't just a few pipes in the ground, there have or should have been careful planning and design gone into the system to allow it to work correctly, more so with low temperature systems and heat pumps.

With underfloor heating there are a few things to consider when getting this installed

  1. Heat Loss
  2. Flow temperature
  3. Insulation in floor for downward losses
  4. Floor build up, depth, type of system
  5. The amount of pipe in the floor and the centres
  6. The pattern of which it is laid
  7. Floor coverings and their effects
  8. Manifold locations

Underfloor heating is around 55% radiant and 45 % convection and because the majority is radiant it creates a much more comfortable environment at much lower temperatures  compared to radiators .

What should be first considered is the heatloss of the property and the rooms in the property as this will give you a guide of how much pipe is needed and what flow temperature is needed to overcome these conditions at design conditions.this is usually done through a calculation that works out your room areas and wall,floor and window types to give a more accurate answer to how much energy your building fabric loses

With this information we can now look at any awkward rooms or index rooms that need excess heat and try and achieve the lowest possible flow temperature to achieve your designed indoor temperature. This can be then installed throughout the whole house and installed in a way to maximise efficiency and work alongside your heatpump to maximize the heat pump's output and efficiency also.

Any ufh that is on a ground floor would ideally need to be insulated underneath to stop any downward losses through the building fabric and to stop any wasted energy and uk building regulations require downward losses do not exceed 10 watt per mtr.Alongside this a perimeter edging strip this allows the screed or concrete to expand and contract during any heat up and cooling down periods but also stops any thermal bridging from the screed to the external walls.

There are also many different systems on the market for all different occasions,many of these are not suitable for heat pumps ideally with a heatpump system you are looking for a much greater flow rate 4 times faster than a gas boiler so pipe sizing is necessary here to be able to overcome the pressure loss at these high flow rates. smaller piped systems might have a much larger pressure loss are would require buffers or separation and require larger pumps to overcome this, all affecting efficiency and increasing energy usage.

There is also a very careful consideration when picking these ufh systems on what there output is per m2 and if putting it in will be enough to overcome your heatloss. Lets take for instance a 16mm mlcp system in screed with 150 centres running at 45 deg the output per m2 is 141.3 watts we have to be careful here what flooring we choose also (but i will come onto that later).Now the same mlcp pipe in a reflective aluminium foil lined in floor voids at 150mm centres running at 45 deg is only 45 watt per m2 so a loss of half just from different systems this is limited as the centres are limited to 150mm and are like this on many systems

But with the right  systems, This is where we can now look at the system and see if we can maximise the space and the output by putting more pipe and closer distances apart to increase the output but by doing this we may be able to lower the flow temperature even more thus increasing efficiency of the heatpump and output.

Along with this we do need to be careful of floor temperatures as some flooring will not tolerate higher temperatures as mentioned above 45 deg in screed 150 centre will achieve a floor temp of 32.3 deg not suitable for any glued system or engineered flooring

Floor coverings also have a massive impact on ufh and are something that i see overlooked time and time again. if your installer has designed your system and assumed you are having tiles everywhere then he assumes your output on a 16mm mlcp system in screed at 45 deg is 141 watts m2 but now you decide to put hardwood flooring the output of that floor is now decreased to 84.1 watts even worse you decide you want 1.5 tog carpet or maybe an engineered 22mm flooring, the same ufh will now only achieve 70 watts half the output you originally had with tiles, so it is very important to get this correct and work with your installer

A few quick example of this for a heat pump:

  • You have a room 5mtrs x 5 mtrs your heatloss for this room is 2.1 kws
  • We decide to run the heatpump at 35 deg to maximize your efficiency (scop rating around 4.5- 450% efficient)
  • Flooring is confirmed tiles and we put all pipework in at 150 centres
  • Output per m2 84.3watt per m2 total 25m2 is 2.1kws perfect
  • All underfloor is laid and now hardwood flooring is being installed
  • Output now per m2 is 50.1watts per m2 total 25m2 is 1.25kw (we aren't hitting heatloss)
  • So now the flow temperature needs raising to 50 deg having a huge impact on you efficiency (scop rating around 3.5 -350% efficient)
  • Output now 85 watts per m2 total 25m2 is 2.12kw

So that's a loss of 100 percent efficiency just by laying a different flooring.

So please make sure your underfloor heating installer knows what he is doing and asks these questions before any installation and understands them.

Low-Temperature Heating Systems

Low-Temperature Heating Systems

Low-temperature heating systems are where all domestic heating systems should be.

It's what's required if we are to install more heat pumps but also has huge benefits to gas boiler installations.

What is a low-temperature Heating System?

A heating system that is designed to meet desired temperatures by using a cooler system water to maintain higher efficencys and the other benefits that come with it.

So rather than having 70°c radiators, your radiators could be 25°c to 55°c yet still give comfort and even improve it.

Low-temperature heating systems typically don't exceed 35-55°c for space heating. This is absolutely achievable for most UK heating systems.

There are 3 ways of achieving a low-temperature heating system. Increased emitter (radiator) sizes, increased insulation, and low-temperature controls. These will all work individually but the best way to get your temperature as low as possible would be to do these altogether.

However, the most important and easy part is to set up and use modulating controls such as weather compensation or load compensation properly.

What this creates and the benefits are :

Comfort at Lower Room Temperatures

There is more radiant heat in each room creating a much warmer environment throughout, you also won't be using your own body heat to warm objects around you as hot goes to cold. this also creates cleaner safer air in the property as the hot air convects air though the property which could be carrying all sorts of allergens

A radiator with more convected heat will heat the air to above comfort temperature. As this cools the air will drop down the other side of the room, and objects like sofas and beds can disrupt this current.

The nature of high temperature, on/off heating is that the radiator also pulses. The room will overshoot the selected room temperature, then undershoot before the heating then kick back in.

A lower temperature system can minimise this 'over and undershooting' effect, and even simply match the heat input from the system, to the heat required to have a nice comfortable steady room.

All this means comfort can be found at lower temperatures and turning the stat down results directly in fuel bills saved.

Improved COP for Heat Pumps

There is more efficiency to be gained from running heat pumps at a lower temperature.

A heat pump running radiators at 55oc could use 40% more electricity than a system at 40°c. And we all know how much electricity costs.

This is to do with the temperature/pressure relationship heat pumps rely on. That is the higher the refrigerant gas pressure, the higher the temperature of that refrigerant gas.

Smaller radiators, or a call for a higher temperature for hot water demand, will mean the compressor has to drive harder to increase the fridge gas temperature. Even a small increase in pressure results in disproportionately higher use of power

Controlling your Heat Pump

Controlling your Heat Pump

How are you controlling yours??

I see so many installations, with one of the most important part of the heat pump locked away in the cupboard under lock and key of the installer, why??

In these controls are advanced electronics and programming to let your heat pump achieve its full potential, so why not use these controls?

Instead I see lots of installs being controlled by "Smart Stats" i.e on/off stats that have the capability to link to your phone making it "smart". These are what makes your heat pump cycle, These are what turn your heat pump on and off decreasing efficiency,These ironically are the least smart thing on the system.

Weather compensation alone is how your heating ideally should be running off. Whether it be Advanced weather compensation from Viessmann or Vaillant or even a basic weather compensation from Mitsubishi or Samsung. And if room influence is needed for compensating highly insulated rooms or rooms with solar gain the main controller should be used not third party unless used for limiting temperature only and have no direct link to the heat pump.

How this works? The first thing to understand is that weather compensation is a more gentle approach that’s proactive. It alters the radiator output before the house drops in temperature therefore not needing a higher temperature to ‘catch up’ with property heat loss.

With weather compensation you have an external temperature sensor. This Sensor is looking at your heat loss variable the Outside temperature, Your installer sets up your heat pump controller so that at design outdoor temperature (in our area is -3) The flow temperature of your heating circuit is at its highest ideally under 50-45 degrees maximum  Achieving the highest efficiency to achieve your desired room temperature. As the outdoor temperature increases your heat loss decreases so your heatpump would respond by lowering your flow temperature with doing so maintaining your desired indoor temperature without any drop in indoor temperature so maintaining that comfort you desire and lowering your energy bill in the process as you are only putting in just the correct amount of energy as you are losing though your building fabric.

What's happening When you have on/off stats controlling your heat pump with weather compensation enabled also?? These work on internal temperature so what happens here is your outdoor temperature drops as doing so it lets your internal temperature drop and then sends a signal to your heat pump to start. Your heat pump will then look at the outdoor sensor and choose its flow Temperature based on the weather compensation curve thats been set up by your installer. The issue now is you have lost to much energy in your house so the return temperature is lower than your weather compensation curve so when the heat pump starts it needs to run at maximum Needing to "catch up" Just as your heat pump catches up and gets your house to temperature and wants to start modulating down for a greater efficiency your indoor stat hits the desired temperature and switches the heat pump off, this is Cycling and will continue throughout the day and night causing inefficiencies and high energy bills and should be avoided. With most installs with on/off stats are also not optimised and the weather compensation is set up to high to "catch up" quicker.

To achieve the highest Scop (efficiency) your heat pump must be running off its own controller and have limited interference from external stats, running of pure weather compensation to maintain a comfortable home at its highest efficiencies, this is what we talk about in the industry as low and slow, letting the heat pump run for long periods of time and its highest level of efficiencies mostly running at its lowest modulation using the as minimal electric as possible to produce the most heat output and maintaining your desired indoor temperature consistently throughout your house. There are always cases where indoor reference is needed mainly in houses with very high insulation levels and low heat demand or with high solar gain and there are ways of using the main controllers for indoor reference or having stats/trvs as limiting indoor temperature so your heat pump maintains good flow rates and long run times in rooms that still need it.

VDI 2035 System Water Quality

VDI 2035 System Water Quality

What is it?? And why is it important??

With all of our new installations we make sure at the end of every job the system water is at its very best. How we do that is by making sure that the whole system has been completely flushed through and all filters are cleaned. We then fill with demineralised water to a German Water Quality Standard vdi 2035.

VDI 2035 isn't a common practice in the UK, We like to pride ourselves in taking those extra steps to provide quality to our heat pump and boiler installations. This means we fill to a high Standard of water parameters and try and go above and beyond to reach them this includes filling your system with demineralised water.

Lowering your conductivity in your system water has many benefits, it provides longevity to your system, stops reactions of metals, inhibits corrosion and removes unwanted salts and minerals from causing scaling to heat exchangers or coils creating inefficiencies within the system.

P-H levels are also a key element of this. To much acidity or alkalinity have huge impacts on certain metals, special conditions apply to aluminium. We aim to make sure the ph levels are maintained at a neutral ph and designed specifically to the metals in the system following the vdi2035 guidelines

Oxygen, This is the biggest contributor to corrosion. The aim is to keep the oxygen content in your system to as low as possible,Sealed systems are a must.You should not be refreshing the system water with fresh oxygenated water regularly.

A yearly Test on every service of system water quality is a must!! With this information we can see what the water quality of the system is and if it has changed from the year before or if new corrosion is present in the system before it gets out of hand and a flush of the system is needed. Helping To Protect the system and keep The system running problem free for years to come.

Why add bottles of System inhibitor that doesn't let you know the ingredients of, and people just top up top up but not test to see what its doing to your system or it affects rather put the purest cleanest water in from the start to stop corrosion rather than just inhibit it with more chemical. We can test some inhibitors and there presence in systems if required.

Heat Loss, why it is so important to calculate with heat pumps

Heat Loss, why it is so important to calculate with heat pumps

What I always advise with any of our customers whether they are just starting the journey of getting a new heating system or upgrading an existing heating system or heat source is to get a heat loss report done on their property first.

The benefits and knowledge of this heat loss is invaluable to any engineer or homeowner looking at getting the maximum efficiency out of their systems and making sure that the property has the correct sized heat source and also the correct size emitter for the property to maintain the desired indoor temperature whatever the outdoor temperature.

What does it involve? To give a brief description we look at all your building materials, windows ,walls, doors ceilings, roofs and floors and how they affect the heat loss in your property, How much resistance they give to the Energy in your property and how fast they will allow you to lose that energy through the building materials of that property.

This is very important with all heat sources but especially heat pumps.It gives you the all the correct information to size these correctly to make sure you are giving the home just the correct amount of energy and creating a comfortable home at your desired temperatures  whilst maintaining high efficiency, it stops you overheating your property with excess energy and reduces your heat source from cycling on/off consistently especially as the outdoor temperature increases and your heat loss is reduced.

There is even more benefits as now we can see in your property what size your emitter needs to be to maintain this temperature, so they can all be sized correctly. we can look at how well insulated your property is and if just a few small upgrades can help.

A fabric first approach is always advisable by adding that extra layer of loft insulation or getting that cavity wall insulation, maybe just improving some windows or doors or even going to a more extreme length and wrapping your property makes all the difference and the lower that heat loss the smaller your heats ource, creating a more efficient home and lower energy bills and a smaller carbon footprint.

Getting this all correct plays a key role in getting the best out of your heating system. Guessing in this day and age or rules of thumb are all out of the window, We can now educate our customer on their home, Give great advice on improvements and help to design a system that will benefit them for years to come and also give them a prolonged life of their system.

Putting all this information together with a perfectly sized heatpump setup using emitters all correctly sized for the property, running on a weather compensated curve give the homeowner not just perfect comfort it give the greatest efficiency that can be achieved and by doing this lowering the energy bills all year round.

Proving Efficiency and performance (Scop) or (cop)

With all this cold weather at the moment, Im seeing and hearing of so many horror story's about Ashp and Gshp costing a-lot to run or not heating their houses to design temperatures.

Why are these installers not being held responsible for their installation?? These Installations are not performing to the Scop (seasonal coefficient performance) that they promote to the customer stating this heatpump can do x..y and z

But what if your installer can prove his previous installs are performing above and beyond expectations, they are held accountable for their installation and they truly are trying to squeeze every bit of efficiency out of their systems.

We offer all our customers the opportunity to include 'Open Energy Monitoring', this shows us their energy usages, there performances, their Cop/ Scop (seasonal co efficient performance) or in layman's terms how much electric to heat generated they are using. How their Units are reacting to certain Weather conditions, Or if they are Under performing ,We can see if there is any cycling happening, or if there unit is running not at the desired temperatures or outputs we predicted or designed for.

This in Return gives us a better insight into the Heat pumps usage but also how its reacting and how we can improve every installation.The information this provides us with is paramount to understanding, and getting the best of any heatpump installation.

Because now as a company we are not guessing or giving excuses about poor performance, We are being held accountable for a top class install and the efficency and performances are clear to see and are easily monitored and proven.

There is no more need for guess work and do things by hear say or rules of thumb or follow a one size fits all schmatic

All the maths, the physics, the hydronics, the correct system design knowledge and information is all out there and the industry needs to step up and give their customers what they deserve.

Here at Custom Renewables that is our aim with every installation.

The importance of a good installer

I am currently getting more and more phone calls, asking me to take a look at their newly installed heat pump, which I am more than happy to do every time, taking my time to optimise settings explain to the customer how the heat pump works, how to set up the weather compensation, the correct control strategy and any recommendations I have on their system.

Most of these phone calls are mainly due to their high electric bills in this cold weather, what I'm confronted with on most occasions is poorly installed installations.

I don't think this should reflect on the installer itself, not all the time. It should reflect on the industry and the lack of proper training and good engineers in the industry. Especially now we are pushing more towards heat pumps and trying to move away from gas boilers and keeping efficiency at the forefront of our minds.

I wouldn't be where I am today without the types of leading industry training from Heat Geek or Northampton Academy teaching correct system design especially for low temperature systems and heat pumps that run at the lower difference of temperature of 5deg. The importance of getting flow rates correct for the perfect transfer of heat and kilowatt exchange.

Set up and commissioning of a Heat pump is also key to any installation and I see Cop (coefficient performance) of less than 2 in a-lot of these I go out too just because the weather compensation is set way to high and there are third party controls switching the heat pump on/off or there pipe work is undersized and there heat pump is struggling to keep up with the heat loss.