ᐅ Assessment of Calculated Heating Load Values According to the Plumbing Engineer
Created on: 8 Jun 2015 20:17
S
splittiHello everyone,
I have had the heating load for my house calculated. Unfortunately, the result falls exactly between two units... Just to mention, a central controlled ventilation system with heat recovery is planned.
Here is the statement from my plumbing specialist:
The calculated heating load is approximately 5.6 kW at -10°C (14°F). At this temperature, the air source heat pump produces about 5 kW, with the remaining 0.6 kW covered by the electric heating element. (The next larger unit delivers around 7 kW heating capacity at -10°C.)
Your possible continuous hot water output is about 254 liters per hour (67 gallons per hour).
These are the technical details, and now I wanted to share these figures with the group. What do you think of these statements? I live in the Ruhr area; it does get cold here. -10°C (14°F) occurs rather rarely, but there have been exceptions with temperatures as low as -20°C (-4°F). Would you agree with this assessment, or would you rather opt for the larger unit?
Thank you very much, and I hope these details are sufficient...
Good luck
splitti
I have had the heating load for my house calculated. Unfortunately, the result falls exactly between two units... Just to mention, a central controlled ventilation system with heat recovery is planned.
Here is the statement from my plumbing specialist:
The calculated heating load is approximately 5.6 kW at -10°C (14°F). At this temperature, the air source heat pump produces about 5 kW, with the remaining 0.6 kW covered by the electric heating element. (The next larger unit delivers around 7 kW heating capacity at -10°C.)
Your possible continuous hot water output is about 254 liters per hour (67 gallons per hour).
These are the technical details, and now I wanted to share these figures with the group. What do you think of these statements? I live in the Ruhr area; it does get cold here. -10°C (14°F) occurs rather rarely, but there have been exceptions with temperatures as low as -20°C (-4°F). Would you agree with this assessment, or would you rather opt for the larger unit?
Thank you very much, and I hope these details are sufficient...
Good luck
splitti
M
merlin66711 Jun 2015 12:08Hello,
Who calculated your heating load?
Does the ventilation system have a reheating coil, preheating coil, ground source preheater, or is the outside air duct buried?
To what extent was this taken into account in the heating load calculation?
What indoor temperature was used?
I know the Ruhr area from the map and have only been there once, so I can’t estimate if it stays cold for long periods (I have fog in mind, which is common there).
What you must not forget: heating load and domestic hot water production are two different things. When you need hot water, energy is supplied to the heating system. Depending on the size of the hot water tank, it can take some time until the water heating is finished and the heat pump is available again for space heating (in the meantime, you may operate the heating system with an electric backup heater).
The decision is not easy and, in my opinion, also depends on how often such conditions occur. For this reason, I use an air-to-water heat pump that can operate down to about -16°C (3°F) without the backup heater activating; it only turns on below that temperature (this winter about six times, but for less than half an hour in total). However, my climate is significantly more extreme – design heating load at -14.6°C (6.3°F), with winters often reaching -20°C (-4°F), usually warming up to about -10°C (14°F) during the day.
If your ventilation system allows adding extra energy independently of the heat pump and the temperature occasionally drops that low only for a short time, I would choose the smaller unit. Otherwise (depending on the price difference), go for the larger one. A coefficient of performance (COP) of about 2.3 at -16°C (3°F) with 35°C (95°F) supply temperature is still better than direct heating with an electric backup heater.
Best regards,
Christian
Who calculated your heating load?
Does the ventilation system have a reheating coil, preheating coil, ground source preheater, or is the outside air duct buried?
To what extent was this taken into account in the heating load calculation?
What indoor temperature was used?
I know the Ruhr area from the map and have only been there once, so I can’t estimate if it stays cold for long periods (I have fog in mind, which is common there).
What you must not forget: heating load and domestic hot water production are two different things. When you need hot water, energy is supplied to the heating system. Depending on the size of the hot water tank, it can take some time until the water heating is finished and the heat pump is available again for space heating (in the meantime, you may operate the heating system with an electric backup heater).
The decision is not easy and, in my opinion, also depends on how often such conditions occur. For this reason, I use an air-to-water heat pump that can operate down to about -16°C (3°F) without the backup heater activating; it only turns on below that temperature (this winter about six times, but for less than half an hour in total). However, my climate is significantly more extreme – design heating load at -14.6°C (6.3°F), with winters often reaching -20°C (-4°F), usually warming up to about -10°C (14°F) during the day.
If your ventilation system allows adding extra energy independently of the heat pump and the temperature occasionally drops that low only for a short time, I would choose the smaller unit. Otherwise (depending on the price difference), go for the larger one. A coefficient of performance (COP) of about 2.3 at -16°C (3°F) with 35°C (95°F) supply temperature is still better than direct heating with an electric backup heater.
Best regards,
Christian
Similar topics