19 Vaillant ecoTec - powerflush or replace?

beckstar1975

We have BG homecare and they've just replaced the power sensor as it was full of sludge - only a month after they last did this. They also replaced the pump the end of last year.

Clearly the system is full of sludge, am London/SE and was last flushed 19 years ago when we had this boiler installed - since then have had an extra floor with an extra bathroom and 2 extra bedrooms installed. Also no filters installed with it.

Would it be worth spending a few hundred on trying a flush and seeing if it improves or is better to bite the bullet and get a new boiler and get it flushed on install and get limescale and magnetic filters installed too? Been quoted about £3.5k on Heatable and BG are coming out to quote tomorrow but are making a fuss as it's a vertical flue (which they installed)

Thanks

FreeBear

If you are contemplating replacing the boiler, I'd strongly recommend looking at replacing it with a heat pump. Some of the quotes coming out of Octopus are competitive or even lower than those for a replacement gas boiler. Although, if you have microbore plumbing (10mm or smaller), that could cause problems..

A flush and fitting of a magnetic filter would certainly keep the boiler going for a little longer, but at 19 years old, it is coming to the end of its life (some would say it is already past it). If BG are going to do a flush & fit a filter, it might cost more than a replacement heat pump.

beckstar1975

No - sadly best quote we can get from Octopus (our current supplier) is £7.5k for the heat pump install (it's £15k total cost minus the £7.5k grant) - sadly no way can afford this. For now we are going to have to replace with a gas boiler, eventually we would want to get a kitchen/diner extension with underfloor heating etc and might look again at heat pumps - tbh I am not sure whether we could fit one in our garden

FreeBear

beckstar1975 said:

No - sadly best quote we can get from Octopus (our current supplier) is £7.5k for the heat pump install (it's £15k total cost minus the £7.5k grant) - sadly no way can afford this. For now we are going to have to replace with a gas boiler, eventually we would want to get a kitchen/diner extension with underfloor heating etc and might look again at heat pumps - tbh I am not sure whether we could fit one in our garden

BG also do heat pumps...

If you finally decide on a gas boiler, do pay attention to the minimum heat output. Most people don't need a 30kW or even 40kW boiler to heat their home. Even a 12-15kW boiler is often too large. But if it is a combi boiler, it needs to be sized based on cold water flow rate, so modulation range is important.

I ended up fitting a Viessmann 050 combi rated at 30kW. Perhaps a little oversized for the cold water flow rate, and hugely overpowered for heating. But it will modulate down to 3.2kW, and when running, ticks over at 4-6kW heating my modest 3 bed semi quite effectively. Many boilers won't modulate down this low and would end up short cycling which kills efficiency and increases wear & tear.

Regardless of which boiler you go for, it is worth fitting larger radiators in some/all rooms - This will enable you to run at a much lower flow temperature and still heat the house effectively. The lower flow temp increases the boiler efficiency and also reduces corrosion & build up of scale. This saves money on your gas bill and reduces repair costs over time.

Lorian

Pressure sensor?

Depends how old the boiler is but I'd be minded to fit a decent magnetic filter and do a chemical flush and then add inhibitor 

beckstar1975

Boiler is 19 years old, and we've had bigger rads installed upstairs and tb the hall is the only place we could fit a bigger one - rest are all big anyway. 

We've got BG and a local company coming out later this week for advice on flush/replace and costings for both

TELLIT01

Replacing a conventional boiler with a heat pump seems rarely to be that simple.  Larger radiators are often needed and the heat pumps become less efficient when the outside temperature drops i.e. just at the time you need them most.  Friends of ours have just moved from a house with a heat pump and have a gas boiler at their new house.  They said they will not have a heat pump again, at least not from choice.

beckstar1975

Also there is a real problem with the rules in citing them when you live in terraced houses, as we are an on a slope and there is nowhere currently in the garden we could cite the pump to be compliant without having to dig/level out the garden. Plus wherever it is would be right outside bedrooms for us and neighbours and that's not fair. And it would literally be in the middle to be 1m plus from either boundary (house is only 5m wide).

I am hoping that by the time we redo the house/move/the replacement boiler dies tech will have come on leaps and bounds and we will have a more eco friendly option. Sadly now that's not possible/

Albermarle

TELLIT01 said:

Replacing a conventional boiler with a heat pump seems rarely to be that simple.  Larger radiators are often needed and the heat pumps become less efficient when the outside temperature drops i.e. just at the time you need them most.  Friends of ours have just moved from a house with a heat pump and have a gas boiler at their new house.  They said they will not have a heat pump again, at least not from choice.

Some of the issue, is that with a heat pump ( compared to a gas boiler) you need to think ahead a lot more.
A Heat pump system takes a long time to heat up a cold house. Maybe even 24 hours ? So best to never let the house get that cold in the first place.

beckstar1975

TBF it takes over an hour to raise the house temperature by a degree with the current boiler, know it's faster than a heat pump but hardly speedy

FreeBear

beckstar1975 said:

TBF it takes over an hour to raise the house temperature by a degree with the current boiler, know it's faster than a heat pump but hardly speedy

That's about the same rate mine heats up. To make it faster, one can either increase the flow temperature, or fit larger radiators. I purposefully run at reduced flow temperatures (in the 40-60°C range) in an attempt to boost efficiency. Also have oversized radiators that were installed with an eye towards the future when a heat pump is the only option.

During December, I tried running the system with a maximum flow temperature of 45°C, raising the room temperatures at about 0.5°C per hour. At one point, heating kicked in with a 35°C flow to maintain the temperature. Boiler was also range limited to 6.5kW. In all, demonstrated that my heating system could function with a heat pump with minimal changes (perhaps a bigger radiator in the bathroom).

As my gas boiler is only a couple of years old, it will be a long while until I fit a heat pump - Don't have the same concerns about where to site it, but finding somewhere to put a DHW tank is an issue. Have space for both earmarked though.