Hybrid Heatpump - viable with combination of underfloor he

[nickamsterdam]

Hi!

Apologies for the English posting - my Dutch is poor despite a few years in the country.

We're currently in the middle of a house rennovation and trying to determine whether to sign for a hybrid heat pump prior to the subsidy reducing at the end of the year.

We've spoken to Adlar (as they had available in person appointments) and DeWarmte (as they were strongly recommended by a friend), with DeWarmte providing a much cheaper quote overall for an 8.3kw unit. Both claimed the setup should be ok for our property.

However, the plumber we have working on the property has come back and said that hybrid heat pumps won't work with a combination of radiators and underfloor heating, conflicting with what we heard from Adlar and DeWarmte. Implication is that the only solution would be to install underfloor heating throughout, which isn't a viable option.

"- to accomplish the total m2 over 4 floors with multiple systems is most likely increasing the bills while using a heat pump system in overdrive
- you will have to regulate in fact 2 different systems in which de radiator system is divided again in multiple sections"

A few details about the property
- 230sqm terraced house built in 1910
- 4 floors: basement and top floor will be heated by radiators, ground and 1st floor will have underfloor heating installed. Current intention is to keep the existing radiators (4 on each floor) - these could theoretically be replaced with fan/convection radiators (type 33 or type 22).
- CV kettle will be replaced with a new gas one (currently two old separate systems, with two old CV ketels)
- Some insulation, but not great (double glazed windows, some roof/floor insulation) - energy label C prior to any of the work
- 14 solar panels on the roof
- Previous tenants used 1765 m3 of gas per year, but this was using old CV ketels and prior to underfloor heating installation. However, it was only two of them at the time.

Old boilers and piping have been taken out, so not currently able to run any tests as to how well the house holds heat.

Does anyone have any experience or a particular view on whether a raiator + underlooor heating combination is viable with a hybrid heat pump?

Thanks,

Nick

[99ruud99]

Well, first of all, hybrid pump is not that much unsimilar to a normal heating unit. Just it has an electric part that takes care of the heating as long as it is strongly enough. When its too cold outside the gas-component will start working.

So, your plumber is correct on electric pumps, but since its hybrid he is incorrect. Just as a side note, ro know that the first months you will have to figure out what the ideal settings are. With a normal high temperature heating system it is more easy. That is why he says dont go hybrid, it gives him a more difficult task.

What you have to figure out is hoe much heating output you need for every room. You have insulation label C, which is average. Should be fine with hybrid.

However, if you have only 1 small radiator for 100 sqm basement, yeah thats not going to work.

My advice, if you want take hybrid, but install some extra radiators. Make sure to let your plumber do a heating calculation (heat loss va heat delivery) for 40°C heating. He might have to install an extra radiator in the basement.... Those cost about 200 euros (installation included) when you are already renovating everything ...

I mean, yeah, you can cut back costs of installation, install minimum amount of radiators and use 70°C radiators. You will think the plumber did a great job since he was very cheap, but in a few years you will have spend more in total costs.

IF your plumber still thinks he wont be able to install, ask for the calculations. You might want to consider some extra insulation. Though, with label C you should be totally fine.

Ps- i have same, label C underfloor at ground level, others have radiators. No problem whatsoever.

[ Voor 3% gewijzigd door 99ruud99 op 18-12-2024 23:11 ]

[nickamsterdam]

Thanks Ruud!

I think the overall count of radiators is probably ok (one reasonable size per room, 3 or 4 per floor total), but the radiators look to be reasonably old and not type 22 or type 33 ones for sure.

Question is then going to be whether replacing them all - another 2k cost presumably - is going to become too long overall.

Are your radiators the low temperature and/or convection ones? Which hybrid heat pump did you go for in the end?

[Ronald]

I think first step is assess expected maximum heat loss (separated for each floor too)

What temperature are you expecting to heat the ground floor to? Most heat demand is normally the lowest heated floor as heat will move upwards in the insulated shell of the house.

What is the function of the ground floor? Modern Dutch building regulations expect habitable rooms to reach 20 degrees in all weather conditions. This is my definition of a proper heating system as one could expect on purchasing a house. If the design cannot do that, in my view that’s a deficiency unless explicitly mentioned before the sale (if even allowed). People may be put off, which could affect value.


With radiators designed for very high temperature water, you’ll struggle to get the ground floor warm at heat pump friendly water temperatures. I have no concerns on the floor heated areas: if the pump can deliver demand it’ll work… 4th floor may get by on the current resistors, especially if roof insulation is brought to modern standards.