People Before Profit MLA Gerry Carroll says this is not just a scandal, but a "crime against the people of this region".

An immediate assembly election is the only "move that makes sense", he says, and voters in Northern Ireland should have their chance to "register their disgust at the ballot box".

He says people are "right to have no confidence" in politicians, and the executive "can't be trusted" to set up an inquiry into the scheme's failure.

The SDLP's Patsy McGlone, a former chair of the Enterprise Committee, described the debate as an "interesting" one.

He says the DUP has adopted an "anything-but-Arlene tactic".

They have been "trying to dump on everyone, that's on officials, consultants, media, every assembly member and committee", he adds.

What a day to make your maiden speech in the assembly!

Seven months on from her election, Joanne Bunting of the DUP rises to speak.

The East Belfast MLA says the problems created by the RHI scheme must be "rectified as quickly as possible", but "very regrettably, that has not been the focus".  

She accuses the media of playing the scandal out "like a soap opera".

"This sensationalist, tantalising approach," she says, "does nothing to foster an environment of conveying the facts with the purpose of finding a resolution."

DUP MLA Paul Frew defends his party leader, saying she is "a minister who Northern Ireland needs to get us through some of the darkest weeks in devolution".

He adds: "I agree with Sinn Féin, this has been a circus today."

Mr Frew says Arlene Foster is best placed to address the problems raised in the RHI scheme.

"You are elected to this place to serve the people - do not walk out of this place like some set of clowns," he tells the members.

Enda McClafferty
BBC News NI Political Correspondent

We were promised a plan to reduce the £400m heating bill, but, much like the Sinn Féin and opposition MLAs, that detail was absent.

What we got was the promise that Economy Minister Simon Hamilton would make a statement in the new year.

But more than that, the first minister admitted that it won’t be easy to make the savings, as they wanted to be "fair to those who responded to the incentive as it was intended to operate".

Making sure Stormont continues to operate may well be just as tough as reducing the heating bill. 

In her roles as an executive minister Arlene Foster has "presided over a catalogue of failures", according to Green Party leader Steven Agnew.

He says that had the first minister "accepted responsibility from the start" for the botching of the RHI scheme, then we "wouldn't have seen the heat that this debate has caused".

The North Down MLA tells the chamber that given Mrs Foster's "track record of such failure time and time again", he can "only conclude that she is an incompetent minister".

Ulster Unionist Roy Beggs says "the integrity of this institution is at stake", adding that the executive is "in a state of turmoil".

The East Antrim MLA reminds members that originally "today was pencilled-in for the draft budget".

He attacks the role of departmental special advisers in the RHI episode, saying Arlene Foster was responsible for them and they were "out of control".

Stormont's institutions are being "pushed to their limits" by the RHI scandal, Alliance Party deputy leader Stephen Farry says.

He points to neighbouring jurisdictions, saying that if a similar situation had arisen "it would lead to the main players stepping aside".

He says Arlene Foster was "tone deaf" to the political implications of her decision not to stand down, the North Down MLA tells members.

"I'm sad and appalled by this motion," says William Humphrey of the DUP.

"This portrayal of my colleague, my leader and our first minister is not what I know and not what the people on these benches know," the North Belfast MLA says.

Talkback
BBC News NI

The RHI fiasco has "turned public dissatisfaction into anger", Claire Hanna of the SDLP claims.

"Cronyism and corruption are written all over this in the minds of the public," the South Belfast MLA adds.

The £400m projected cost to the taxpayer is "horrifying", she tells members.

"The fact that apparently because it was London money it was OK to squander is really breathtaking and it's arrogant," Ms Hanna says.

"The fact is that somebody earned that money and paid it in, and all taxpayers are entitled to know that their money is being fairly spent."

Simon Hamilton of the DUP says the debate has consisted of "a litany of erroneous charges, charges that are without evidence".

He rejects calls for the first minister to take full and sole responsibility for the failure of the RHI scheme.

The Stangford MLA points to the role of experts from inside and outside Deti, the department that set the scheme up, and reminds members that "the house voted for the regulations that set up the scheme".

The economy minister also rejects allegations that Arlene Foster intervened to stop the closure of the scheme "for some nefarious reasons", and insists that the first minister will not be standing aside.

Jayne McCormack
BBC News NI

"Corruption" is at the heart of the RHI scandal, according to Sinn Féin's John O'Dowd, who wants to know more about when the critical cost flaw in the scheme was identified.

"The general public is highly suspicious that someone, or a group of individuals, benefited to the tune of hundreds of thousands of pounds of public money," he says.

"Were there members or supporters of the Democratic Unionist Party or other political parties in this chamber who were taken aside and shown the details of this scheme?"

He adds an independent judicial figure from outside Northern Ireland is the only way to get to the bottom of the RHI scandal.

"That's how you do business in relation to placing accusations in front of people," he says.

Ulster Unionist Jenny Palmer is next up to have her say, and starts off by saying the first minister has dealt a "devastating blow" to Northern Ireland's international business reputation.

"Why would businesses look to come here," she asks, "when the first minister has made such a catastrophic policy decision?"

She is "not a safe pair of hands" to be in charge of the public purse, Mrs Palmer says.

And she asks: "What must the United Kingdom Treasury think of us and our apparent inability to manage public funds?"

The DUP's Lord Morrow has an interesting metaphor to describe the attitude of those bringing the motion.

"When you throw a stone into a pack of dogs you always know which one you've hit - it's the one that gowls the loudest," he explains.

"What we had right around this chamber today is a lot of people gowling and shouting," the Fermanagh and South Tyrone MLA observes.

"The institutions have taken an absolute kicking here," according to Sinn Féin's Michelle O'Neill.

She says she is "embarrassed" by the standard of the debates, telling MLAs that they are "losing the run of yourselves" during the proceedings today that have been "about antics" and "about stunts".

"I am not interested in the internal wrangling of the DUP," she says, but instead delivering for the electorate.

Therefore, she says, the first minister must "step down to allow an investigation that would help to restore public confidence, and the Northern Ireland population needs to be assured that their money is not being wasted".

Paul Givan of the DUP says the public "rightly want people to be held to account" for the failings of the scheme.

He is interrupted by the the UUP's Andy Allen, who asks how many units of social housing could be built with the money used up in "the £400m black hole".

Mr Givan says it is clear that the motion is to be used in respect of a whole range of other issues, and that "it's about undermining Arlene Foster".

The Lagan Valley MLA, who is Northern Ireland's communities minister and oversees broadcasting in the region, goes on to attack the BBC's coverage of the RHI story, saying it is  "presenting allegations as facts".