ᐅ General Contractor Offer – Heating and Plumbing: Is It Acceptable?
Created on: 8 Oct 2018 02:58
D
Dirk5000
Hello everyone,
Our general contractor has made the following offer. Is this a good price, acceptable, or too expensive? What do you think?
Single-family house, 220 sqm (2,368 sq ft), Saxony
Heating:
Vaillant brine-to-water heat pump VWF88/4 including drilling (3x 70 m (230 ft)) and underfloor heating; complete with installation
= 33,000 EUR (net) (of which 5,000 EUR for heating installation)
Sanitary:
2 bathrooms (2x walk-in showers, 1 bathtub, 2 washbasins, 2 rimless toilets, 1 urinal, towel radiator) — all standard; without bathroom furniture; complete with installation
= 13,000 EUR (net) (of which 4,500 EUR for sanitary installation)
Thanks!
Our general contractor has made the following offer. Is this a good price, acceptable, or too expensive? What do you think?
Single-family house, 220 sqm (2,368 sq ft), Saxony
Heating:
Vaillant brine-to-water heat pump VWF88/4 including drilling (3x 70 m (230 ft)) and underfloor heating; complete with installation
= 33,000 EUR (net) (of which 5,000 EUR for heating installation)
Sanitary:
2 bathrooms (2x walk-in showers, 1 bathtub, 2 washbasins, 2 rimless toilets, 1 urinal, towel radiator) — all standard; without bathroom furniture; complete with installation
= 13,000 EUR (net) (of which 4,500 EUR for sanitary installation)
Thanks!
@Fuchur
That was my thought as well, which is why I asked about the heating load. Possibly, the heat pump with over 8 kW might be slightly oversized, and a smaller model could be chosen, which would also require fewer bore meters.
@Dirk5000
The result of the heating load calculation was not included with your details yet. Try searching for heating load calculation according to DIN 12831. You can find examples of such documents there. Alternatively, the pink forum also offers an online tool to roughly calculate it. Some general contractors tend to oversize the heat pump. My general contractor wanted to do the same, but with some persuasion, I was able to choose a smaller model.
That was my thought as well, which is why I asked about the heating load. Possibly, the heat pump with over 8 kW might be slightly oversized, and a smaller model could be chosen, which would also require fewer bore meters.
@Dirk5000
The result of the heating load calculation was not included with your details yet. Try searching for heating load calculation according to DIN 12831. You can find examples of such documents there. Alternatively, the pink forum also offers an online tool to roughly calculate it. Some general contractors tend to oversize the heat pump. My general contractor wanted to do the same, but with some persuasion, I was able to choose a smaller model.
What bothers me most is the extraction rate of just 41.9 W/m (12.8 W/ft). If the ground is really that poor, then maybe an alternative should be considered. 50-55 W/m (15.2-16.8 W/ft) is the typical average, and our drilling company plans with 45 W/m (13.7 W/ft) as a safety margin. With that alone, you could manage with just two boreholes. By the way, there are companies in Saxony that can drill up to 250 m (820 ft) with a single borehole. But at least two times 99 m (325 ft) is more of a standard.
Fuchur schrieb:
What bothers me most is the extraction rate of just 41.9 W/m. If the ground is really that poor, then maybe an alternative should be considered. 50-55 W/m is the normal average; our drilling company plans with 45 W/m as a safety margin. With that alone, you would only need 2 boreholes. By the way, there are companies in Saxony that drill up to 250 m with a single borehole. But at least 2 x 99 m is more or less the standard again.The “reverse calculation” isn’t quite correct. You have to subtract 20% (COP 5) from the 8.8 kW heating capacity of the heat pump. These 20% of the heat come from the supplied electricity, while the remaining 80% come from the ground. That leaves about 33 W/m. Either there are a lot of safety factors built in, or the underground is really not very suitable for a probe.
Addition regarding heating:
- Heating capacity = 8.9 kW (according to Vaillant calculation)
Originally, we applied for 2 boreholes of 80 meters (260 feet) each at the district office. However, the district office recommended 3 boreholes of 70 meters (230 feet) each.
The approval has already been granted, and the funding application has been approved.
- Heating capacity = 8.9 kW (according to Vaillant calculation)
Originally, we applied for 2 boreholes of 80 meters (260 feet) each at the district office. However, the district office recommended 3 boreholes of 70 meters (230 feet) each.
The approval has already been granted, and the funding application has been approved.
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