Heat Pump Advice for Homeowners

The information below is provided as a guide to homeowners to get the best possible performance from their heat pump systems throughout the year to ensure there is plentiful hot water and your home is warm when occupied.

We are only a phone call away and are more than happy to assist heat pump owners in the operation of their systems so do not hesitate to call us should you have any questions.

If you need the user manual for your heat pump visit our heat pump user guides and manuals download page.

1. House is too warm or not warm enough


We receive a lot of calls where the heat pump system is delivering too much heat into the property on milder days. This is invariably due to incorrect configuration of the heat pump controller due to the weather compensation function being turned off and/or the heating curves being incorrectly set up. This can be easily remedied during a service visit by reprogramming the heat curves and enabling weather compensation.

The same is often applicable for properties not achieving target temperature and again can usually be remedied by modifying the heat curves to increase system flow temperatures on cooler days.

Another possible cause of not reaching target temperature can be due to incorrect scheduling of the hot water cylinder reheat. If, for instance the system is timed to reheat the hot water cylinder between 6.30am and 8.00am in the morning then priority will be given to the hot water system over the heating system. Again, this is easily resolved by modifying the programme schedule such that the hot water reheat times are set to on when peak heating is not required, for example mid afternoon or early morning.

2. House never gets warm on colder days

This is generally due to three reasons and can be resolved by modifying or adding to the existing system.

The radiators are undersized

We see a lot of retrofit installations where an existing oil or LPG boiler has been replaced with a heat pump system. Typical flow temperatures for fossil fuel boilers are generally in the range 60 to 80 Deg C, whereas, a low temperature heat pump system will usually operate in the range of 40 to 60 Deg C. This means that a heating system designed and installed for an oil or LPG boiler may not be able to deliver the heat required from the installed radiators running off the new heat pump on colder days. A way to resolve this is to up size the radiators in the rooms which are not getting up to temperature. The radiators do not necessarily have to be longer or taller but can be changed from a single panel to a double or even triple panel unit. Alternatively a small fan assisted coil unit could be installed. This is effectively a radiator with an electric fan running over it which can ouput more heat than an equivalent size radiator.

The heat pump is undersized

We have encountered some installations where the installed heat pump unit is undersized for the property. This means that on colder days the heat loss from the house exceeds the amount of heat energy that the installed heat pump can deliver.

In this situation there are a number of options:

- The existing heat pump unit is swapped out for a unit of higher capacity.

- An additional heat pump is installed to operate in conjunction with the original unit to ensure heat demand is always met.

- A more pragmatic approach is to leave the existing system as is and provide a supplementary air to air heat pump system. A 5kW air to air wall mount unit will deliver almost 6kW of heat energy from a 1.7kW electrical supply making it extremely efficient to run. This is quite often the cheapest and most practical way to achieve rapid heat up times in a large kitchen / family room or lounge with the minimum of disruption. This type of system also has the advantage of being able to cool in summer and provide air filtration. We have a range of models in our showroom which can demonstrate the effectiveness of air to air heating.

Incorrect configuration of the electric backup / booster heater

We always ensure our heat pump systems are specified and installed to meet the heat demand without the need for supplementary direct electric booster heaters as this will ensure running costs are kept to a minimum. However, we do see cheaper installed equipment which relies on supplementary direct electric back up heaters to switch in if the heat pump is unable to meet the heat demand. In our routine servicing work we have encountered many properties where the backup heaters are incorrectly wired, incorrectly fused and sometimes not even connected at all. This means at peak demand the property will not maintain target temperature as the direct electric booster heater cannot be switched in. This is something that our service engineers can generally easily resolve during a service visit.

3. High Running Costs

A less common issue that is sometimes due to incorrect setup and configuration of the system which can usually be resolved by a customer programme setting or engineer service visit. However, there are also a number of physical issues due to poor installation practise which can lead to higher running costs and these are listed below.

Cylinder immersion heater always set to on

This is where the hot water cylinder is being solely heated by the cylinder immersion heater rather than the heat pump unit. Using the direct electric immersion heater for hot water will lead to increased running costs. We recommend programming the hot water progammer on the heat pump controller to heat the hot water cylinder. The cylinder immersion heater is generally in place for legionalla prevention or emergency back up.

Booster heaters permanently on

daikin booster heater set allways on

We have encountered systems where the direct electric booster heaters are programmed to always come on, or, come on before they are required.

Blocked filters

blocked filter

System filters can become blocked if the heat pump and heat pump system is not regularly serviced. When this happens the system flow rate will reduce resulting in poor efficiency and higher running costs.

Loss of refrigerant

This is a more serious problem. A small leak in the refrigerant circuit may not manifest itself for some time and in the interim period will result in increased running costs as the unit compressor has to work harder to deliver the required heat output. If we suspect a loss of refrigerant from the heat pump we will carry out tests to determine how and where the leak has occurred and effect a repair.

Physical obstructions to the outdoor unit

screen in front of daikin monoblock heat pump obstructing airflow
screen in front of daikin monoblock heat pump obstructing airflow

As you can see from the pictures, this poor Daikin monoblock has had its front fans completely obstructed by a wicker screen. This will cause the cold air blown out at the front to be recirculated into the rear of the unit resulting in increased compressor load and running costs. If left like this the unit operating life will also be reduced.

Insulation issues on pipework to outdoor unit

Missing or damaged insulation on exterior pipework will result in heat loss and increased running costs.

Buried fridge pipework not correctly protected against water ingress

If refrigerant pipework to the external unit is buried it must pass via waterproof ducting. System efficiency can be reduced by up to 30% when buried pipe insulation becomes waterlogged. This is because as the insulation around the pipework becomes saturated with water a heat bridge to the surrounding ground is formed allowing heat intended for the property to be dissipated and wasted in the ground.

4. Radiators get warm when the hot water cylinder is being heated

Faulty or incorrectly configured zone valves are a possible cause. We have also found that some systems have been installed incorrectly leading to heat loss in the heating system during the hot water cycle. This can lead to radiators heating up in the summer months when space heating is not required and whilst being annoying will also reduce system efficiency and result in a reduction of available hot water.

The importance of annual servicing

As you can see many of the problems we come across are easily resolved. The key to trouble free heating and hot water is to ensure your heat pump system has an annual maintenance visit and any of our recommendations are implemented. This will ensure that the system is able to operate in an efficient manner and reduce the likelihood of failures and breakdowns.

Why not visit our showroom

Call 01242 821438 to book an appointment

Heidi Air Conditioning Showroom Internal

We are open Monday to Friday from 8:00am to 5:00pm