ᐅ Combining a heat pump with a hydronic fireplace

Mycraft schrieb:

Because this pre-war technique is hardly or no longer useful in modern houses, it is energetically nonsensical. The whole thing is a nightmare in terms of control systems and ultimately brings almost no benefit. No, not everything that existed in the past and was considered good makes sense today.

Because:
- it is hardly used anyway (the house heats up far too quickly)
- the effect is only marginal (the water pockets must not be too large and the water must not become too warm)
- the investment and operating costs are high since a lot of additional hydraulics are needed, which also consume electricity during operation.

Honestly, I don’t quite agree with that. Especially since this very concept is promoted by a company.
Why would anyone want to create a mess? The water is not drained; the control system mixes cold and warm water.

So I cannot understand or agree with your negative points.

seth0487 schrieb:

As far as I know, you shouldn’t feed cold water into the fireplace system, but preheated water (~60°C (140°F)) instead. This is unfavorable for a heat pump that operates with underfloor heating and supply temperatures of around 35-40°C (95-104°F).
A fireplace generates a lot of heat. Therefore, the water heated to support the heating system is actually too hot for the heat pump’s supply temperatures and is mixed with cold water. This works, but from an energy standpoint, it doesn’t make much sense. Moreover, the cozy effect created by radiant heat is reduced with this technique because less radiant heat is released compared to a conventional fireplace.
It’s better to invest in a photovoltaic system. Combined with a heat pump, it makes much more sense.

The problem with modern houses and fireplaces is that they usually emit too much heat. You can quickly turn your living room into a sauna. For example, if we have many guests (which, thanks to COVID, I hardly remember when was the last time), the temperature in the living room rises by a few degrees quite fast.

The point about preheated water is correct, but during the “start-up” phase, it is cold.
The heat from the fireplace is then stored in a buffer tank and can also be used to heat domestic hot water if needed.

You’ve basically already made your decision if I look at your responses here. Otherwise, of course the company advertises that—they want to make a sale. A combination of high-temperature and low-temperature systems is always complicated and therefore prone to errors, usually more expensive to install, and less efficient.

T_im_Norden schrieb:

You have basically already made your decision if I look at your replies here.

No, I haven’t, but I can’t agree with some of the points...

Michlhausbauaa schrieb:

The heat from the fireplace is then stored in a buffer tank.

Anything that involves a buffer tank is energetically inefficient when a heat pump is part of the system. First, you heat water only to cool it down again so it matches the requirements of the underfloor heating and the heat pump. This whole process needs to be carefully coordinated, which often does not work well even when using just a heat pump.

Additionally, the heat from the fireplace itself in the installation room has to be considered.

The overall result: expensive, complex technology and planning/implementation, no energy savings (at best higher costs), and so on.

@Michlhausbauaa

Belief can certainly move mountains. Arguments and expertise don’t stand a chance against that. As for the companies, you might be surprised, but it’s not just one. As long as something can be sold, it will be marketed, even if the product may be completely pointless.

But I agree with the previous commenters. It seems you have already made your decision.