Conventional to combi conversion. Inlet size reassurance.

[Gallois]

Thanks everyone. None of the fitters have physically seen the pipe. I took the kitchen skirting off and took a picture after I'd been given the news about needing a new pipe. I have sent the picture to the fitters, but I think they have been thinking the same as you guys and going from what is apparent from the photo. I hadn't measured the pipe until this morning. The recommendations remain the same. Two say new pipe, one says he thinks the existing pipework would suffice.

I have a few more quotes to collect, and feel more informed about what to ask now. I'll make sure to show the next fitters the actual pipe to see if that makes a difference.

I think the reality is that if I don't want a new pipe I'd have to find someone who is willing to give the existing pipes a go first and build in the contingency of having to fit a new pipe if it's not up to the regs. What an expensive faff.

 

[simond]

I'm with Geoff (Gasguru). That is almost certainly a coupler or an elbow coming out of the floor so it is not the external pipe circumference you are measuring, but the coupler.

Combi and a gas hob off that is optimistic to say the least, unless the meter is a metre away.

 

[Gallois]

To follow up guys, I had another fitter in this morning and he took a look at the pipe. It's 1/2" steel going to 15mm copper, so will probably need replacing.

He's suggested I have a gas pressure test built into the quote with the contingency of a new supply pipe, which seems a sensible approach.

 

[Agile]

That's 3/4 barel comming out of the floor, which will pass a bit more gas than 22mm copper.

I had always thought that steel will give a greater flow resistance due to its rougher internal finish?

Tony

 

[Dan Robinson]

You need to revisit your pipe sizing tables T.


I'm not going to mention vices though

 

[FiremanT]

To follow up guys, I had another fitter in this morning and he took a look at the pipe. It's 1/2" steel going to 15mm copper, so will probably need replacing.

He's suggested I have a gas pressure test built into the quote with the contingency of a new supply pipe, which seems a sensible approach.

Don't waste cash even trying to use it - it will be too small. Maximum run of 15mm pipework will be about 3M without any other demand

 

[Gallois]

Thanks I've come to the same conclusion. In fact I'm now thinking of having a conventional replacement so I won't have the hassle.

I'm going to be a nightmare customer asking for more quotes but I didn't know any of this stuff when I started out.

Anyone care to recommend a good conventional boiler with at least a 5yr warranty?

 

[Dan Robinson]

Intergas or Atag

 

[Gallois]

This is an update for interested people, but may be a bit off topic wrt my original post.

I've swayed from combi to conventional a few times over the last week. I'm trying to see the advantages and disadvantages of both but I still can't seem to decide. I was all up for staying conventional, but had someone to do the loft insulation who said there was black dust on the insulation from moisture. I went to have a look and the cold water tank lid doesnt fit. It's a round one, I'm presuming the tank has deformed and now it won't clip on. So after starting with combi and then thinking conventional would be better in this house (3 bed 1 bath+ensuite, the risk of leaks with pressurised system, difficult for pump overrun connection, loss of showerpump and new 22mm gas pipe needed) I was set on conventional for conventional swap. Now the water tank is probably up the spout and the mould issue I'm just inclined to rip it all out and risk a combi. The One thing I have decided is boiler make, will be Viessman, WB, Vaillant or Ideal.

Does anyone have any advice on what I should do? I'm really confused and just feel like I'm going round in circles. The mould may be from an U insulated loft hatch but I think the water tanks in the loft are contributing too.

 

[flameport]

The lack of a properly fitting lid will certainly lead to condensation in the loft.
In the context of new boiler, radiators etc., a replacement tank in the loft is an insignificant amount of money.

Two bathrooms from one combi = not going to work at the same time.
If you have a bath, filling it from a combi will take far longer than it does now.
A shower from a combi will be nothing like that from a pumped shower.
An electric shower is far worse before you consider one of those.
When a combi breaks, you have no hot water or heating.

 

[Agile]

A replacement loft tank fitted at the same time is probably about the same cost as the difference in the price of a combi compared with a heat only boiler.

Then there is the extra labour cost of converting the house from conventional system to a combi. I price that at £400 in my budgetary telephone costings.

But I would never recommend a combi for any house with more than two residents or more than two bathrooms.

I appreciate that there are many houses with a combi boiler but all I can say is that the hot water performance will be far better with a stored hot water system.

A normal combi will give about 9 to 14 litres per minute of hot water whereas a stored system should give 14 to 22 li/min which will serve two outlets so that a kitchen tap can be used without disturbing someone having a shower.

Tony

 

[Gallois]

You guys are really helpful. Thank you.

I think I was just having a knee jerk reaction to finding the next thing that needs sorting. I live alone so it's unlikely that I'll get the disruption of a tap being turned on, but the other points are valid so I probably just need to sort the tank in the loft out.

 

[muggles]

The One thing I have decided is boiler make, will be Viessman, WB, Vaillant or Ideal.
.

The Viessmann is the best of a bad lot here, but make sure you go with the 200-W series as the 100-W series have had a few wobbles.

Personally I'd have an Intergas

 

[Gallois]

No one has recommended an Intergas yet - there is an installer in my area. What model would you recommend? I have a Potterton Prima 30F at the moment. Do the Intergas heat only boilers require a direct pump overrun connection?

 

[muggles]

Dan_Robinson recommended them, along with Atag, further up this page...

If you have a 30F, you're happy with its current heating effect and you're not planning to extend then based purely on your current boiler's output you'd be looking at the 18OV. The best way to calculate the size requirement, however, is to use a Whole House Boiler Sizing Calculator. Most boilers will require a pump overrun