ᐅ Plumbing Rough-In Inspection: What Should We Pay Attention To?
Created on: 18 Aug 2022 10:19
F
fromthisplace
Hello everyone,
We are now having the shell inspection with the plumber. We already selected the fixtures back in March.
1. About the heating:
Our initial scope of work listed two models. The reason given was: "Depending on which one fits your house better." The contract now specifies the Stiebel Eltron LWZ 5S. So, I assume that a heating load calculation has been done and that this system fits our house, or am I mistaken?
2. About the inspection:
I understand that we will finalize the exact locations for the water connections and toilets. One point is the utility sink in the technical room. We would prefer a full-sized table here and need to discuss whether the plumber will install this or if we are allowed to buy it from the furniture store.
3. About the underfloor heating:
As the client, do we have any say in this? I would like to express that I prefer a low flow temperature and to ask if they can lay the loops quite close together. Of course, this is more like telling the contractor how I would like their work to be done.
Thank you all.
We are now having the shell inspection with the plumber. We already selected the fixtures back in March.
1. About the heating:
Our initial scope of work listed two models. The reason given was: "Depending on which one fits your house better." The contract now specifies the Stiebel Eltron LWZ 5S. So, I assume that a heating load calculation has been done and that this system fits our house, or am I mistaken?
2. About the inspection:
I understand that we will finalize the exact locations for the water connections and toilets. One point is the utility sink in the technical room. We would prefer a full-sized table here and need to discuss whether the plumber will install this or if we are allowed to buy it from the furniture store.
3. About the underfloor heating:
As the client, do we have any say in this? I would like to express that I prefer a low flow temperature and to ask if they can lay the loops quite close together. Of course, this is more like telling the contractor how I would like their work to be done.
Thank you all.
S
SaniererNRW12323 Aug 2022 23:56fromthisplace schrieb:
2. I reasoned: "A pipe spacing of 15-20 cm (6-8 inches) and a supply water temperature of 35°C (95°F) are generally too high because closer spacing and lower supply temperature are better." Is there a mistake in my thinking, or could the argument that "15-20 cm (6-8 inches) suits our house best" still be correct?No, you don’t have a mistake. How is the pipe spacing planned in the bathroom? At 15 cm (6 inches), it will be tight to achieve a comfortable temperature. There is no valid reason not to specify a supply water temperature of 30°C (86°F) (plus your desired indoor temperature) and then design the heating system accordingly.
fromthisplace schrieb:
He said he basically understood that, but whether it makes sense he would have to calculate (or have it calculated) again,You might want to ask him if it really makes sense to drive constantly at 200 km/h (120 mph) on the highway or if the fuel consumption is probably lower at 120 km/h (75 mph). It’s exactly the same with the heating system – at 35°C (95°F) supply temperature, your heating costs are higher. At 30°C (86°F), heating costs are lower, although the initial investment is somewhat higher (more piping, larger manifold, etc.).X
xMisterDx25 Aug 2022 00:14SaniererNRW123 schrieb:
Why don’t you ask him whether it makes sense to drive at 200 km/h (125 mph) on the highway all the time, or if the fuel consumption might actually be lower at 120 km/h (75 mph). It’s the same principle – at 35°C (95°F) you have higher heating costs. At 30°C (86°F), heating costs are lower, but there is a somewhat higher upfront investment (more piping, larger manifold, etc.). That’s true, but comparing 120 km/h (75 mph) to 200 km/h (125 mph) is a bit exaggerated.
As far as I know, when it comes to a heat pump, increasing the supply temperature from 35°C to 55°C (95°F to 131°F) results in roughly 14% higher heating costs. That’s not ideal, no question.
In a well-insulated new building (150 m² (1,615 ft²) with 50 kWh/m²/year) meaning about 7,500 kWh per year, that actually only adds up to around 1,000 kWh more heat annually, which for a heat pump translates to roughly 300 kWh more electricity consumption.
Yes, it’s not ideal and should be avoided if possible and if you keep it in mind. But it’s far from the comparison you made. At 120 km/h (75 mph) I consume under 4 liters of diesel per 100 km (59 mpg), while at 200 km/h (125 mph) it’s easily over 7 liters per 100 km (34 mpg).
S
SaniererNRW12325 Aug 2022 09:00xMisterDx schrieb:
As far as I know, with a heat pump you get about 14% higher heating costs if you increase the supply temperature from 35 to 55°C (95 to 131°F). That’s definitely not ideal.Unfortunately, that information is not correct. A 5-degree increase corresponds to about 12.5% higher electricity consumption (around 2.5% per degree). Therefore, increasing from 35 to 55 degrees results in approximately 50% more consumption (which matches the figures from my own heat pump when it produces hot water at 50°C (122°F)).==> The comparison to a car is quite fitting. 😉
X
xMisterDx25 Aug 2022 09:13I found a comparative study from Fraunhofer on this topic… annual performance factor shown over supply temperature. Your 50% doesn’t match with that.
However, there is a wide variation, as it also depends on the heat pump. But what do they know, right? 😉
However, there is a wide variation, as it also depends on the heat pump. But what do they know, right? 😉
S
SaniererNRW12325 Aug 2022 09:24xMisterDx schrieb:
I found a comparative study from Fraunhofer showing the annual performance factor plotted against the supply temperature. Your 50% figure does not match that.
There is quite a bit of variation, depending on the heat pump as well. But what do they really know, right? Just Google “increased consumption heat pump supply temperature” (or similar). The results consistently show about 2.5% increase per degree. You’ll find articles from the last 15 years always citing this number. And if you look at the electricity consumption of your own heat pump, you can verify these figures yourself.
X
xMisterDx25 Aug 2022 09:52I’ve got it... found a good study by Fraunhofer and a chart from ifeu.
With an air-to-water heat pump, the seasonal performance factor drops from 3.5 at a supply temperature of 35°C (95°F) down to 2.8 at 55°C (131°F).
Okay, that’s not 14%, but 20%... still nowhere near 50%.
With geothermal energy, it’s clearly worse, that’s true. It drops from 4.8 to 3.2. That’s 50%. But very few use geothermal, and 3.2 is still higher than 2.8 for air-to-water.
It was a field study, so measurements from real devices. I suspect they’ve been using the geothermal number as a standard for the past 15 years and applied it to air-to-water too? Wouldn’t surprise me, since contractors and companies tend to exaggerate things to their advantage 😉
PS:
The same nonsense is done by solar installers when they assume constant annual output for photovoltaic systems and then calculate all sorts of savings... no one tells you that most energy is fed into the grid during summer, and there’s almost no yield in winter... right when you need it most 😉
With an air-to-water heat pump, the seasonal performance factor drops from 3.5 at a supply temperature of 35°C (95°F) down to 2.8 at 55°C (131°F).
Okay, that’s not 14%, but 20%... still nowhere near 50%.
With geothermal energy, it’s clearly worse, that’s true. It drops from 4.8 to 3.2. That’s 50%. But very few use geothermal, and 3.2 is still higher than 2.8 for air-to-water.
It was a field study, so measurements from real devices. I suspect they’ve been using the geothermal number as a standard for the past 15 years and applied it to air-to-water too? Wouldn’t surprise me, since contractors and companies tend to exaggerate things to their advantage 😉
PS:
The same nonsense is done by solar installers when they assume constant annual output for photovoltaic systems and then calculate all sorts of savings... no one tells you that most energy is fed into the grid during summer, and there’s almost no yield in winter... right when you need it most 😉
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