Dear heat pump experts and experienced home builders,
I would like to better understand what heat pump capacity we actually need.
Our project:
2 full floors
No basement
148 sqm (1,593 sq ft)
KFW55 standard
In our energy demand calculation, a 6 kW air-to-water heat pump is recommended.
However, the heating load calculation in the plan specifies an 8 kW air-to-air heat pump.
Both calculations seem to follow a standard procedure, as this is a developer project.
Which figures in both documents should I focus on?
To me, 8 kW seems quite high, but this is just a feeling formed by reading here in the forum.
The underfloor heating is already installed, also standard, and the screed has been curing for 4 weeks, waiting for the system to be heated up.
But there is no heat pump installed yet.
The builder would credit us €15,000 if we handle the purchase and installation of the heat pump ourselves.
All these questions are overwhelming us.
Is this even possible? Can we choose a different model or manufacturer?
Is it worthwhile, is €15,000 a reasonable amount?
Is 6 kW enough? ...
We need solid information to stand our ground with the builder.
Help!
Thanks!
I would like to better understand what heat pump capacity we actually need.
Our project:
2 full floors
No basement
148 sqm (1,593 sq ft)
KFW55 standard
In our energy demand calculation, a 6 kW air-to-water heat pump is recommended.
However, the heating load calculation in the plan specifies an 8 kW air-to-air heat pump.
Both calculations seem to follow a standard procedure, as this is a developer project.
Which figures in both documents should I focus on?
To me, 8 kW seems quite high, but this is just a feeling formed by reading here in the forum.
The underfloor heating is already installed, also standard, and the screed has been curing for 4 weeks, waiting for the system to be heated up.
But there is no heat pump installed yet.
The builder would credit us €15,000 if we handle the purchase and installation of the heat pump ourselves.
All these questions are overwhelming us.
Is this even possible? Can we choose a different model or manufacturer?
Is it worthwhile, is €15,000 a reasonable amount?
Is 6 kW enough? ...
We need solid information to stand our ground with the builder.
Help!
Thanks!
This might not help you much, but I happened to come across heating system suppliers online yesterday and was surprised to see that, for example, the Vaillant Arotherm plus VWL75 is offered at a relatively low price and listed as stock item / immediately available. What could be the downsides?
A
Alessandro8 Dec 2022 08:38With 11kW, you can nearly heat a new building with 10 residential units. So it is far too large for your calculation!
Did the builder actually order this, or is he just telling you what would be available?
Did the builder actually order this, or is he just telling you what would be available?
Do you know exactly who placed the order? In our case, a planning office (complete incompetents) did the heating system design and told the plumber which heat pump to order. At that point, he only had the information about what to order. After he installed the heating system and didn’t follow any of the (poor) specifications from the planners, I would assume that he wouldn’t have ordered such a wrongly sized heat pump if he had known.
If your situation is similar, I would try to get in touch with the plumber and work with them to find a solution. Whether you can reach them, of course, I don’t know.
If your situation is similar, I would try to get in touch with the plumber and work with them to find a solution. Whether you can reach them, of course, I don’t know.
netuser schrieb:
This might not help you, but I came across heating system suppliers online yesterday and was surprised that, for example, the Vaillant aroTHERM plus VWL75 is listed relatively cheaply and as in stock / directly available.
Is there any reason not to go with it? There’s no objection; all options are being considered.
I’m not quite clear with Vaillant’s model numbers yet. How many kW does it have?
Alessandro schrieb:
With 11 kW, you could almost heat a new building with 10 residential units. So it’s way too big for your calculation!
Did the builder really order that, or is that just what he was told was available? If it weren’t so sad. But that’s exactly what was ordered.
Pacmansh schrieb:
Do you know who exactly placed the order? In our case, a planning office (complete idiots) sized the heating system and then told the plumber which heat pump to order. At that point, the plumber just ordered what he was told. After he installed the heating system and ignored all (bad) instructions from the planners, I would guess he wouldn’t have ordered such an incorrectly sized heat pump if he had known better.
If your situation is similar, I’d try to get in touch with the plumber and look for a solution with him. Though I don’t know if you can reach him, of course. The heat load calculation comes from an MEP (mechanical, electrical, and plumbing) consultant — the heat load itself is probably correct, but how he arrived at 11 kW using the Daikin “heating solution navigator” is unclear to us.
The construction manager is asking about this. I wonder if she herself can’t realize that 11 kW is implausible?
The plumber blindly ordered it.
A real chain of idiots.
We are building with a general contractor/trade contractor (fluid transitions depending on what is more economical for the company).
So far, the company has been very reserved regarding the heat pump, subcontractors, etc. Now they are more open given the situation. And now that we got the heat load calculation, all this nonsense is coming to light—of course, much too late.
But we can get in touch with the plumber; hopefully, we can find a solution together.
There is also a company that installs customer-supplied heat pumps.
We are checking various suppliers to see what is available.
Here are excerpts from the heating load calculation.
The summary of the heating load calculation.
Then image 2, an excerpt from the heating navigator by Daikin.
There are completely different values again, suddenly an outdoor temperature of -8.6°C (16.5°F) is used.
And image 3
The "solution": the 11 in the center stands for 11kW.
I don’t understand this.
Wärmepumpe.seeker
at the next karma level
The summary of the heating load calculation.
Then image 2, an excerpt from the heating navigator by Daikin.
There are completely different values again, suddenly an outdoor temperature of -8.6°C (16.5°F) is used.
And image 3
The "solution": the 11 in the center stands for 11kW.
I don’t understand this.
Wärmepumpe.seeker
at the next karma level
The Vaillant 75 produces 7 (7.5?) kW but can modulate down to very low levels. However, for large houses, you need to check if the maximum flow rate is sufficient (it only delivers 1270).
Delivery times are often inaccurate. This is based on my experience from last year. Availability seems to be even worse at the moment...
Delivery times are often inaccurate. This is based on my experience from last year. Availability seems to be even worse at the moment...
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