New Central Heating / Hot Water system

[ckl139]

Not sure thats what I wnat?

How about just sticking to the OV solution, any answers or suggestions to my question?

 

[Dan Robinson]

Is it ok to go with the pressure vessel on the Rad Circuit?

Yes.

Shall I change all the CH pipes (£550) to do so?

Dunno - do they work?

Shall I go for the Baxi or Vallaint boiler (vallaint will cost around 200 extra)

Vaillant if those are the only options you want to consider.

With 9 rads and a 160ltr tank I was specced a 18kw boiler, do you think I can go for a 200 litre tank on the 18kw?

Cylinder size will make naff all difference.

 

[ckl139]

Is it ok to go with the pressure vessel on the Rad Circuit?

Yes.

Shall I change all the CH pipes (£550) to do so?

Dunno - do they work?

Shall I go for the Baxi or Vallaint boiler (vallaint will cost around 200 extra)

Vaillant if those are the only options you want to consider.

With 9 rads and a 160ltr tank I was specced a 18kw boiler, do you think I can go for a 200 litre tank on the 18kw?

Cylinder size will make naff all difference.

Yes they do work but they are very old so thought as we are doing it, may as well just get new pipes in?

The other option was worecester bosch.

So by going for a larger cylinder the 18kw boiler would still be ok, I was worried about recovery time etc.

 

[Dan Robinson]

Reheat times will be longer, but not thank much longer. It isthe heating you size for... 18kW will be plenty.

 

[ckl139]

Thanks for your response.

By heating size I assume you are taking my number of rads and home type as the guidance to determine the boiler output?

 

[Dan Robinson]

Yes mate.

 

[ckl139]

Thanks.

Got another guy coming around tonight hopfully to get another opinion and quote but it looks like we will be renewing the system but staying OV.

Main thing we need to decide is whether to go for the 162litre or even bigger?

any suggestions on how we would approach this decision?

RANGE cylinders are the ones the company will be using.

The contractors we are looking to use are not an independent as such, but they are a local company with many engineers working for them. Nothing like British Gas though !

 

[ckl139]

Ok so I think unvented is out of the question as we do not have a 22/25mm running through the house, I also think its probably excessive for our needs (1 bathroom) house.

The final heating engineer / plumber visited. His suggestion was also a combi for us 837 vallaint. Im awaiting the quote but in the meantime I checked out my neighbours combi (BAxi 105he) - completely dissapointed, I tested it by fully opening hot water tap downstairs in kitchen and then the same upstairs bathroom sink - this one was barely giving out any hot water, Id say just a bit more than a constant smooth dribble.

IS this how all combis are??

So our choice now is:

1. The OV system as per my OP.

2. A highoutput combi most like the valliant 837. The exclusive 838 doesnt seem to be as good and the 937 is just to big to fit anywhere.

What are peoples thoughts on these two options and my question about combi performance?

 

[doitall]

I'm not sure you are being advised or whether they are trying to maximise the profit.

What is the flow rate at the kitchen tap in ltrs/min peak and off peak times.

You say you use lots of hot water, with 6 in the house, forget a combi of any size.

post the flow rate, and if anyone has bothered the dynamic pressure as well.

If the storage tank cannot recover the draw-off fast enough, I would certainly say it rules out any pressurized hot water system.

 

[ckl139]

Thanks for the reply - why do you say forget the combi with 6 ppl, even though there is one bathroom (+ 1 kitchen obv). I am not disagreeing, I would just like to know the reasoning behind this.


There was a reading done but cant remember.

However, I managed to fill 5 litres of COLD water in 20 seconds from main cold tap in kitchen today at around 6pm - not sure if this helps in anyway?

 

[doitall]

15Ltrs/min is not too bad and one wonders why the storage tank is running dry, perhaps it's a very small tank, or if the pressure is poor, it would be a lot less by the time it got the loft.

15Ltrs min is borderline for an average size combi, no point going for the bigger models, and you could only use one outlet at a time without affecting the others.

 

[ckl139]

15Ltrs/min is not too bad and one wonders why the storage tank is running dry, perhaps it's a very small tank, or if the pressure is poor, it would be a lot less by the time it got the loft.

15Ltrs min is borderline for an average size combi, no point going for the bigger models, and you could only use one outlet at a time without affecting the others.

Which is running dry? I didnt say that.

also could you elaborate on why combi for 6 ppl is no good?

so 15 lttrs a min - is that quite poor then?

 

[doitall]

we told both that we require a lot of hot water and that our current system keeps running out of hot water

Sorry read it wrong.

A combi's fine for one outlet at a time, and opening the kitchen tap is a good way to get anyone out of the shower in a hurry.

 

[ckl139]

So are you suggested the OV system instead?

Update for Flow.... just tested now approx 1035 PM but in upstairs bath tub tap single feed (mains) I done 5 litres in approx 12 - 13 seconds... thats a big difference.

I should say that the kitchen tap test I did earlier was a mono block type tap........

does this change things?

 

[ckl139]

any suggestions given my two options

1. OV as stated in OP (to add to this, do people still fit new OV systems?)

2. Combi Boiler

See my comments with regards to flow.