Priority Hot Water Central Heating Quote

Priority Hot Water Central Heating Quote

Author
Discussion

Eddie Twadds

Original Poster:

147 posts

106 months

Sunday 29th September
quotequote all
Just after a price sense check as I look to upgrade my aging system boiler to either a Viesmann 200 or Vailant Ecotec Pro. Skip to the end if you just want to see the prices.

Although a biggish house (3 floors, 176m2, 5 beds), it's modernish (2008) and well insulated and recent heat loss calculations show an 8kW heat loss. I was considering an air source heat pump (hence heat loss calcs) but they were starting at £7.5k (included upgrades to 18 rads) after the BUS grant so the boss has ruled that out.

A local heating engineer (who has been great) has quoted me for either of these options, which includes removal of old, refit to same position in utility, pipework changes to convert S plan to X plan, magnetic filters, magna clean, weather compensation and associated controllers. Heating is to 20 rads and HW to a 300l unvented cylinder.

Viessmann 200 10kW system boiler £4500
Vaillant Eco Tec Plus 10kW system boiler with various Vaillant wiring centres and controls £4250

Both inc VAT. Just wondering whether these feel about right. I am based in W Yorks BTW.




OutInTheShed

9,323 posts

33 months

Sunday 29th September
quotequote all
What is the basis of your 8kW heat loss?
What's the worst you've seen in reality?
I've seen close to 8kW in reality, basically very cold, pretty windy and heating cranked up due to aged inlaws staying.
About 190kWh per day, averaged over 5 whole days!
That's in Devon, you're nearer the arctic...

Do you have any other heat source?

While I think most people would agree most domestic boiler are over sized, I would think twice about going as low as 10kW for an 8kW heat loss.
If your hosue starts from cold, how long will it take to get warm?

Eddie Twadds

Original Poster:

147 posts

106 months

Sunday 29th September
quotequote all
I had 2 surveys done for a heat pump and both came back with a 7.8kW heat loss based on the MCS heat loss calculator and the Heat Engineer calculator. If I was going for a heat pump then it would have been an 8 or 10kW unit. However, I agree that 10kW on the boiler sounds a little bit low.

Do the prices seem about right?

Happy Jim

1,005 posts

246 months

Sunday 29th September
quotequote all
Do a quote on Boxt and see what that throws up (I’m guessing at £3500)

Mont Blanc

1,400 posts

50 months

Sunday 29th September
quotequote all
10kw for a 5 bed house? Are you sure that has been specced right?

My boiler is a Baxi MegaFlow and it's 32kw!

Eddie Twadds

Original Poster:

147 posts

106 months

Sunday 29th September
quotequote all
The actual heat requirement for the rads is less than 10kW. When the cylinder is heated all the power from the boiler is diverted to the hot water and thereafter back to the rads. Individually they’ll never require more than the max boiler output (that’s the theory).

Eddie Twadds

Original Poster:

147 posts

106 months

Sunday 29th September
quotequote all
Happy Jim said:
Do a quote on Boxt and see what that throws up (I’m guessing at £3500)
Boxt can’t quote for the priority hot water system on their site. They just want to throw a standard install in 🤪

Sheepshanks

34,979 posts

126 months

Sunday 29th September
quotequote all
Mont Blanc said:
10kw for a 5 bed house? Are you sure that has been specced right?

My boiler is a Baxi MegaFlow and it's 32kw!
Unless it's piped in 28mm it can't put 32kW into the pipework!

Ours is 30kW (I didn't choose it, builder had it fitted) and once it ramps up the flow temp goes up a degree a second so within a few seconds it's modulating down.

That said, 10kW does sound low - we had an old Potterton Suprima before which I think was 12kW (fixed) and we came back from holidays one autumn and it had been unusually cold. It took 24hrs to warm the house up - the boiler just sat there not able to get the flow above 50C.

Mont Blanc

1,400 posts

50 months

Sunday 29th September
quotequote all
Sheepshanks said:
Mont Blanc said:
10kw for a 5 bed house? Are you sure that has been specced right?

My boiler is a Baxi MegaFlow and it's 32kw!
Unless it's piped in 28mm it can't put 32kW into the pipework!

Ours is 30kW (I didn't choose it, builder had it fitted) and once it ramps up the flow temp goes up a degree a second so within a few seconds it's modulating down.

That said, 10kW does sound low - we had an old Potterton Suprima before which I think was 12kW (fixed) and we came back from holidays one autumn and it had been unusually cold. It took 24hrs to warm the house up - the boiler just sat there not able to get the flow above 50C.
Don't start asking me technical questions.... biggrin

Ours was all designed/specced a few years ago by a company that does that sort of thing. House is just over 3000 sq ft. All underfloor downstairs, rads upstairs. Insulated hot feed also goes underground to the detached garage for sink etc in there.

Sheepshanks

34,979 posts

126 months

Sunday 29th September
quotequote all
Mont Blanc said:
Sheepshanks said:
Mont Blanc said:
10kw for a 5 bed house? Are you sure that has been specced right?

My boiler is a Baxi MegaFlow and it's 32kw!
Unless it's piped in 28mm it can't put 32kW into the pipework!

Ours is 30kW (I didn't choose it, builder had it fitted) and once it ramps up the flow temp goes up a degree a second so within a few seconds it's modulating down.

That said, 10kW does sound low - we had an old Potterton Suprima before which I think was 12kW (fixed) and we came back from holidays one autumn and it had been unusually cold. It took 24hrs to warm the house up - the boiler just sat there not able to get the flow above 50C.
Don't start asking me technical questions.... biggrin

Ours was all designed/specced a few years ago by a company that does that sort of thing. House is just over 3000 sq ft. All underfloor downstairs, rads upstairs. Insulated hot feed also goes underground to the detached garage for sink etc in there.
At a glance it looks like it can modulate itself down to 5kW which is pretty good. Ours is 7.5kW min and I put the kitchen / diner rads on to take the edge off as it was getting chilly, and it's was quickly cycling on and off as 7.5kW is too much.

rossyl

1,162 posts

174 months

Sunday 29th September
quotequote all
Vaillant controls are expensive, and must be used for fully modulating/PDHW

Alpha or Intergas would be just as good, easier to install and cheaper.

Look for someone who has done Kimbo's Heating Academy.

PT1984

2,552 posts

190 months

Sunday 29th September
quotequote all
We have a Vitodens 100-W B1HF and it’s been rock solid. It’s built like a tank.

Ours is S plan so no priority. It’s a 25kw, because Heatable, but is range rated to 60%. It never goes above 45% modulation. So that I think is 11.25kw, but theres discussion of that on the other thread. I think they overshoot when needed. Anyway, 11 rads and a 205L unvented tank. Honestly, it heat the rads and tank up at the same time no issues. Set to 60c flow.

However if the HW priority means you can set CH and HW at different temps it’s probably worth it for that.

Edited by PT1984 on Sunday 29th September 21:48


Edited by PT1984 on Sunday 29th September 21:49