Change from vented to unvented boiler? Your opinions welcomed.

[6ply]

About 6 years ago we had a new gas boiler and vented tank installed to replace an old oil fired heating and hot water system. The boiler comes with a 10-year warranty and I'm happy with installation and service from the local company we use. The boiler works just fine but the airing cupboard located behind the kitchen (we are in a bungalow) gets minimal use and we are still using an electric shower despite having lots of hot water in the tank. Water pressure at the hot water taps is insufficient to drive a gravity fed shower and would need a boost pump to make it viable. I would like to ditch the electric shower as they fail every couple of years, presumably due to the hard water, and electrically-heated water seems like a bad idea when we have a tank of hot water. I should add we are a family of four, with a couple of pre-teens and a wife who enjoys long showers. Also, I would like to fit a second shower in the bathroom.

The kitchen badly needs updating and I'm considering removing a stud wall and losing the airing cupboard. We would gain about 2.8 m^2 in the kitchen. The boiler could be moved elsewhere in the kitchen or relocated to the loft. Rather than relocate the existing hot water tank and continue with the lack of pressure at the hot water taps, I'm considering changing from a vented to unvented cylinder installed in the loft on a platform currently occupied by the cold water tank. I have had a quote for the work from the same company that fitted and services the boiler. It is higher than I was hoping for and I would welcome your comments on the price and whether moving to an unvented cylinder would generally be a good idea, bearing in mind our requirements.

 

[6ply]

I should mention the unvented cylinder needs to be a horizontal-type due to a relatively low-pitch roof. A 170 L tank is the largest model we can reasonably fit through the loft hatch after it has been modified (currently just a few mm too tight).

 

[gaz1]

watch this for some info

pumped tank to pressurised water tank

 

[Gareth J]

Why not fit a twin pump in? It'll more than likely outperform an unvented mains pressure shower and be less expensive than changing out a relatively new cylinder.

 

[DanZac]

If your going to all that work, wouldn't it be easier to just fit a combination boiler and do away with the tank full stop?

I know that the boiler works as is and isnt that old, but by the time you've bought a flue kit and unvented tank etc your probably not far off new boiler territory anyway (or am I miles off?).

 

[addjunkie]

If your going to all that work, wouldn't it be easier to just fit a combination boiler and do away with the tank full stop?

I know that the boiler works as is and isnt that old, but by the time you've bought a flue kit and unvented tank etc your probably not far off new boiler territory anyway (or am I miles off?).

Not a fan off combis, but I bet theres not much difference in tank price vs new boiler, we worth the discussion with the guy whos quoted.

 

[6ply]

Why not fit a twin pump in? It'll more than likely outperform an unvented mains pressure shower and be less expensive than changing out a relatively new cylinder.

I understand your reasoning. Only problem is the kitchen needs doing and we see this as a one time opportunity.

 

[6ply]

If your going to all that work, wouldn't it be easier to just fit a combination boiler and do away with the tank full stop?

I know that the boiler works as is and isnt that old, but by the time you've bought a flue kit and unvented tank etc your probably not far off new boiler territory anyway (or am I miles off?).

I have no experience with combis but the boiler guys seem to be steering me away from them. However, I agree they should be considered and I can't see it being any more expensive.

 

[6ply]

watch this for some info

pumped tank to pressurised water tank

I'll watch later. Thanks.

 

[6ply]

If I understand correctly the main concern with a combi type boiler is that it might not be able to provide sufficient hot water in times of peak demand such as two kids showering and someone running the taps at a wash basin or kitchen sink at the same time.

 

[addjunkie]

If I understand correctly the main concern with a combi type boiler is that it might not be able to provide sufficient hot water in times of peak demand such as two kids showering and someone running the taps at a wash basin or kitchen sink at the same time.

Yes and also how good your supply pressure is. Low supply pressure dont bother.

 

[Blobber]

Weve have a combi boiler in this house and previous house so 25 years in total, great for instant hot water and space saving as its surprising how much space all the other associated kit takes up BUT I do believe they are all hot water priority so if for instance you are going out and everyone is going to shower/bathe in quick succession then you do loose the heating while the abluting is going on
From our experience the combi is cheaper to run

 

[8ob]

Yes and also how good your supply pressure is. Low supply pressure dont bother.

That's right, mains fed isn’t for everywhere, certainly not around here. I am currently sorting out the plumbing in a property, have gone with one negative head 1.5 bar pumps feeding the cold supply to the showers and another pump supplying the cold feed to the unvented cylinder. Cold storage tank is actually lower than the cylinder. checked the blurb and its acceptable, upside is a guaranteed equal hot/cold pressure to the whole system.

Bob

 

[gaz1]

low water pressure mains has issues both with hot water and cold water feeds

a mixer shower can really play up on them rather well

alternatives are simple

tank in loft and emmersion heater hot water cylinder

pumped system or the newer type pressure fitted hot water cylinder both comes with there own issues

whilst the pumps need replacing too the pressure vessel need replacing vs the cost of the tank and mixer valve for the shower

remember new tanks 20-30 years

pressure vessel and prv vs the cost of new pumps

 

[6ply]

low water pressure mains has issues both with hot water and cold water feeds

a mixer shower can really play up on them rather well

alternatives are simple

tank in loft and emmersion heater hot water cylinder

pumped system or the newer type pressure fitted hot water cylinder both comes with there own issues

whilst the pumps need replacing too the pressure vessel need replacing vs the cost of the tank and mixer valve for the shower

remember new tanks 20-30 years

pressure vessel and prv vs the cost of new pumps

30 years and I'll not be around to worry about it.

 

[6ply]

I have previously asked about upgrading our current system with a pump and was warned that even good quality ones don't last long around here.

 

[gaz1]

I have previously asked about upgrading our current system with a pump and was warned that even good quality ones don't last long around here.

if you run them on the cold feed side they last longer but not on the hot side as scale kills them